Mitochondrial Respiration

Biological systems exhibit quantum-coherent processes that persist and function at physiological temperatures, challenging the conventional view that coherence is too fragile for living conditions. This comprehensive review presents a unified framework for understanding quantum effects across four major domains of quantum biology: photosynthetic energy transfer, avian magnetic navigation, olfactory detection, and mitochondrial respiration. Rather than simply tolerating quantum effects despite the "noisy" cellular environment, biological systems have evolved sophisticated molecular architectures that actively preserve and exploit quantum coherence for enhanced function. We identify recurring design principles across these systems: structured protein scaffolds that create correlated environmental fluctuations, ordered water networks that reduce electromagnetic damping, and crystalline assemblies that prevent random motion while enabling controlled quantum dynamics. These coherence-preserving architectures enable quantum subsystems to feed directly into classical biochemical and bioelectrical networks, enhancing energy efficiency, sensing precision, and information transfer. The framework reveals life as a multi-layered, quantum-classical information system where femtosecond quantum dynamics couple to cellular and organismal processes through mathematical optimization principles. Particularly significant are implications for neuroscience and cognition, where mitochondrial quantum effects could influence synaptic plasticity and potentially consciousness itself through quantumenhanced energy metabolism and coherent bioelectric signaling. We provide testable experimental predictions and outline validation approaches using two-dimensional electronic spectroscopy, isotope substitution studies, and multi-modal bioelectric recordings. Applications span bio-inspired quantum computing, quantum sensors approaching biological sensitivity limits, and therapeutic interventions targeting quantum-coherent biological processes. This interdisciplinary synthesis establishes quantum biology as a mature field with profound implications for understanding life's fundamental operating principles.

Sexual dimorphism is apparent in humans, however, to date no studies have investigated mitochondrial function focusing on intrinsic mitochondrial respiration (i.e., mitochondrial respiration for a given amount of mitochondrial protein) and mitochondrial oxygen affinity (p50 mito ) in relation to biological sex in human. A skeletal muscle biopsy was donated by nine active women, and ten men matched for maximal oxygen consumption (VO 2max ) and by nine endurance trained men. Intrinsic mitochondrial respiration, assessed in isolated mitochondria, was higher in women compared to men when activating complex I (CI P ) and complex I+II (CI+II P ) (p < 0.05), and was similar to trained men (CI P , p = 0.053; CI+II P , p = 0.066). Proton leak and p50 mito were higher in women compared to men independent of VO 2max . In conclusion, significant novel differences in mitochondrial oxidative function, intrinsic mitochondrial respiration and p50 mito exist between women and men. These findings may represent an adaptation in the oxygen cascade in women to optimize muscle oxygen uptake to compensate for a lower oxygen delivery during exercise.

Intermittent fasting is used to reduce body mass in obese adult humans and animals. However, information on the impact of one type of intermittent fasting (IF) called everyother-day feeding (EODF) on young animals is scarce. In this study, 1-month-old mice of both sexes were subjected to a 4-week regimen of EODF using age-matched counterparts fed ad libitum as controls. At the end of EODF exposure, experimental male and female mice weighed 14 and 13% less than the control counterparts. The EODF regimen resulted in lower liver levels of glycogen, glucose, and lactate, but did not affect lactate level in mouse cerebral cortex of both sexes. Activities of key glycolytic enzymes (hexokinase, phosphofructokinase, and pyruvate kinase) in liver of experimental mice were lower than those in controls. In the cerebral cortex, only hexokinase and pyruvate kinase activities were lower than in controls, but phosphofructokinase activity was not affected in IF females and was higher in IF males as compared with ad libitum fed males. Mitochondria isolated from liver of IF mice had lower respiratory control ratios, but those from the cortex had the same values as control animals. The concentration of β-hydroxybutyrate and the activity of β-hydroxybutyrate dehydrogenase were lower in the IF mouse liver, but not changed or enhanced in the IF cerebral cortex. Thus, animal responses to IF do not depend significantly on sex and are directed to decrease energy metabolism to save resources, and the effects are more pronounced in the liver than in the brain.

The aim of this study was to evaluate for the first time the anti-inflammatory effects of chestnut (Castanea sativa) and Eucalyptus (Eucalyptus occidentalis) honeys collected in Italy on murine RAW 264.7 macrophages stressed with the bacterial endotoxin lipopolysaccharide (LPS). Pre-treatment with the two honeys markedly decreased apoptosis and stimulated wound healing in macrophages stressed with LPS, where they also reduced the intracellular levels of ROS and nitrite. Additionally, treatment with LPS decreased the levels of glutathione and suppressed the antioxidant enzyme activities, which were significantly (p < 0.05) increased in the presence of the two honeys, through the modulation of Nrf2 expression; in LPS-stressed macrophages, Chestnut or Eucalyptus honeys protected against inflammation by regulating the main inflammatory biomarkers, including TNF-α, IL-10 and iNOS, through the decrease of NF-кB expression. Finally, they improved mitochondrial respiration and the main related parameters.

Permeabilized muscle fibers (pfi) are widely used to assess mitochondrial (mt) respiratory function in skeletal muscle of various models in different physiological and pathological conditions. Facing the numerous data available for mt-respiration from the literature, it remains challenging to determine what the right values are for a specific respiratory protocol. Moreover, mt-respiration values are highly dependent on pfi preparation, which required good technical skills. In the frame of COST Action MITOEAGLE, one of the objectives of WG2 is the generation of reference values for mitochondrial respirometry in permeabilized skeletal muscle sample preparations. The idea is that new researchers in the field follow a reference protocol and check if their values are in an acceptable range. This approach could serve to test researchers&#39; technical skills and therefore determine if they are proficient enough to perform their own experiments with confidence.

This review discusses the present knowledge on the oxygen uptake kinetics at the onset of exercise in skeletal muscle and the contribution of a previously developed computer model of oxidative phosphorylation in intact skeletal muscle to the understanding of the factors determining this kinetics on the biochemical level. It has been demonstrated recently that an increase in the total creatine pool [PCr + Cr] and in glycolytic ATP supply lengthen the half-transition time of the O 2 on-kinetics, while an increase in mitochondria content, in parallel activation of ATP supply and ATP usage, in muscle oxygen concentration, in proton leak, in resting energy demand, in resting cytosolic pH, and in initial alkalization diminish this parameter. It has also been shown that the half-transition time is near-linearly proportional to the absolute difference between the phosphocreatine concentration during work and at rest (ΔPCr). The present review discusses whether the O 2 on-kinetics on the muscle level is strictly or only approximately exponential. Finally, it is postulated that a short transition time of the O 2 on-kinetics in itself does not need be profitable for the skeletal muscle functioning during exercise, but usually a short transition time is correlated with factors that improve exercise capacity. The transition time is a phenomenological parameter resulting from the biochemical properties of the system and not a physical factor that can cause anything in the system.

Metabolic flexibility is the ability of a cell to adapt its metabolism to changes in its surrounding environment. Such adaptability, combined with apoptosis resistance provides cancer cells with a survival advantage. Mitochondrial voltage-dependent anion channel 1 (VDAC1) has been defined as a metabolic checkpoint at the crossroad of these two processes. Here, we show that the hypoxia-induced cleaved form of VDAC1 (VDAC1-ΔC) is implicated in both the up-regulation of glycolysis and the mitochondrial respiration. We demonstrate that VDAC1-ΔC, due to the loss of the putative phosphorylation site at serine 215, concomitantly with the loss of interaction with tubulin and microtubules, reprograms the cell to utilize more metabolites, favoring cell growth in hypoxic microenvironment. We further found that VDAC1-ΔC represses ciliogenesis and thus participates in ciliopathy, a group of genetic disorders involving dysfunctional primary cilium. Cancer, although not representing a ciliopathy, ...

Permeabilized muscle fibers (pfi) are widely used to assess mitochondrial (mt) respiratory function in skeletal muscle of various models in different physiological and pathological conditions. Facing the numerous data available for mt-respiration from the literature, it remains challenging to determine what the right values are for a specific respiratory protocol. Moreover, mt-respiration values are highly dependent on pfi preparation, which required good technical skills. In the frame of COST Action MITOEAGLE, one of the objectives of WG2 is the generation of reference values for mitochondrial respirometry in permeabilized skeletal muscle sample preparations. The idea is that new researchers in the field follow a reference protocol and check if their values are in an acceptable range. This approach could serve to test researchers&#39; technical skills and therefore determine if they are proficient enough to perform their own experiments with confidence.

Permeabilized muscle fibers (pfi) are widely used to assess mitochondrial (mt) respiratory function in skeletal muscle of various models in different physiological and pathological conditions. Facing the numerous data available for mt-respiration from the literature, it remains challenging to determine what the right values are for a specific respiratory protocol. Moreover, mt-respiration values are highly dependent on pfi preparation, which required good technical skills. In the frame of COST Action MITOEAGLE, one of the objectives of WG2 is the generation of reference values for mitochondrial respirometry in permeabilized skeletal muscle sample preparations. The idea is that new researchers in the field follow a reference protocol and check if their values are in an acceptable range. This approach could serve to test researchers&#39; technical skills and therefore determine if they are proficient enough to perform their own experiments with confidence.

Purpose The purpose of this study was to investigate, in obese adults, changes in body composition, physical capacities, fat oxidation and ex vivo mitochondrial respiration induced by a 3-month either moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT); afterwards, the patients were followed for four months. Methods Thirty-two patients (mean age 39 years; mean body mass index [BMI] 36 kg•m −2) participated in this study attending ~ 34 sessions of training. At baseline (PRE), at the end of the program (POST) and after follow-up, body composition, peak O 2 uptake (V′O 2 peak) and fat oxidation rate were measured. Vastus lateralis biopsies for the evaluation of mitochondrial respiration were performed only at PRE and POST. Results At POST, body mass (BM) and fat mass (FM) decreased (− 6 and − 14%, respectively, P < 0.05) in MICT and HIIT; V′O 2 peak increased in both groups (+ 6 and + 16%, respectively, P < 0.05). Maximal fat oxidation rate increased only after HIIT (P < 0.001). Maximal ADP-stimulated mitochondrial respiration normalized by citrate synthase increased (P < 0.05) by 67% and 36% in MICT and HIIT, respectively, without significant difference. After follow-up, BM and FM were still lower (− 4 and − 20%, respectively, P < 0.050) compared with baseline in both groups. Only after HIIT, V′O 2 peak (+ 8%) and maximal fat oxidation rate were still higher (P < 0.05). Conclusions HIIT was more effective in improving and maintaining V'O 2 peak and fat oxidation. These results may be relevant for an appropriate prescription of training programs designed to optimize aerobic fitness in obese subjects.

M2-like tumor-associated macrophages promote tumor progression by establishing an immunosuppressive tumor microenvironment. The phenotype and activity of immunosuppressive macrophages are related to their mitochondrial metabolism. Thus, we studied if drugs targeting mitochondrial metabolic pathways can repolarize macrophages from M2 into an M1-like phenotype or can prevent M0-to-M2 polarization. The drugs selected are clinically approved or in clinical trials and target M2-specific metabolic pathways: fatty acid oxidation (Perhexiline and Trimetazidine), glutaminolysis (CB-839), PPAR activation (HX531), and mitochondrial electron transport chain (VLX-600). Murine bone marrow-derived macrophages were either polarized to M2 using IL-4 in the presence of the drugs or polarized first into M2 and then treated with the drugs in presence of IFN-γ for re-polarization. Targeting both fatty acid oxidation with Perhexiline or the electron transport chain with VLX-600 in the presence of IFN-γ, impaired mitochondrial basal, and maximal respiration and resulted in M2 to M1-like re-polarization (increased iNOS expression, NO production, IL-23, IL-27, and TNF-α secretion), similar to LPS+IFN-γ re-polarization. Moreover, drug-induced macrophage re-polarization resulted in a strong tumor-cytotoxic activity. Furthermore, the polarization of M0-to M2-like macrophages was impaired by CB-839, Trimetazidine, HX531, and Perhexiline, while Hx531 and Perhexiline also reduced MCP-1 secretion. Our results show that by targeting cell metabolism, macrophages could be re-polarized from M2-into an anti-tumoral M1-like phenotype and that M0-to-M2 polarization could be prevented. Overall, this study provides rational for the use of clinically applicable drugs to change an immunosuppressive tumor environment into a proinflammatory tumor environment that could support cancer immunotherapies.

Permeabilized muscle fibers (pfi) are widely used to assess mitochondrial (mt) respiratory function in skeletal muscle of various models in different physiological and pathological conditions. Facing the numerous data available for mt-respiration from the literature, it remains challenging to determine what the right values are for a specific respiratory protocol. Moreover, mt-respiration values are highly dependent on pfi preparation, which required good technical skills. In the frame of COST Action MITOEAGLE, one of the objectives of WG2 is the generation of reference values for mitochondrial respirometry in permeabilized skeletal muscle sample preparations. The idea is that new researchers in the field follow a reference protocol and check if their values are in an acceptable range. This approach could serve to test researchers&#39; technical skills and therefore determine if they are proficient enough to perform their own experiments with confidence.

Apolipoprotein (apo) E4, the major genetic risk factor for Alzheimer's disease (AD), alters mitochondrial function and metabolism early in AD pathogenesis. When injured or stressed, neurons increase apoE synthesis. Because of its structural difference from apoE3, apoE4 undergoes neuron-specific proteolysis, generating fragments that enter the cytosol, interact with mitochondria, and cause neurotoxicity. However, apoE4's effect on mitochondrial respiration and metabolism is not understood in detail. Here we used biochemical assays and proteomic profiling to more completely characterize the effects of apoE4 on mitochondrial function and cellular metabolism in Neuro-2a neuronal cells stably expressing apoE4 or apoE3. Under basal conditions, apoE4 impaired respiration and increased glycolysis, but when challenged or stressed, apoE4-expressing neurons had 50% less reserve capacity to generate ATP to meet energy requirements than apoE3-expressing neurons. ApoE4 expression also decreased the NAD + /NADH ratio and increased the levels of reactive oxygen species and mitochondrial calcium. Global proteomic profiling revealed widespread changes in mitochondrial processes in apoE4 cells, including reduced levels of numerous respiratory complex subunits and major disruptions to all detected subunits in complex V (ATP synthase). Also altered in apoE4 cells were levels of proteins related to mitochondrial endoplasmic reticulum-associated membranes,

Background and Objectives: Hyaluronan preserves the proliferation and differentiation potential of mesenchymal stem cells. Supplementation of low-concentration hyaluronan (SHA) in stem cells culture medium increases its proliferative rate, whereas coated-surface hyaluronan (CHA) maintains cells in a slow-proliferating mode. We have previously demonstrated that in CHA, the metabolic proliferative state of stem cells was influenced by upregulating mitochondrial biogenesis and function. However, the effect of SHA on stem cells' energetic status remains unknown. In this study, we demonstrate the effect that low-concentration SHA at 0.001 mg/ml (SHA0.001) and high-concentration SHA at 5 mg/ml (SHA5) exert on stem cells' mitochondrial function compared with CHA and noncoated tissue culture surface (control). Methods and Results: Fast-proliferating human placenta-derived mesenchymal stem cells (PDMSCs) cultured on SHA0.001 exhibited reduced mitochondrial mass, lower mitochondrial DNA copy number, and lower oxygen consumption rate compared with slow-proliferating PDMSCs cultured on CHA at 5.0 (CHA5) or 30 μg/cm 2 (CHA30). The reduced mitochondrial biogenesis observed in SHA0.001 was accompanied by a 2-fold increased ATP content and lactate production, suggesting that hyaluronan-induced fast-proliferating PDMSCs may rely less on mitochondrial function as an energy source and induce a mitochondrial functional switch to glycolysis. Conclusions: PDMSCs cultured on both CHA and SHA exhibited a reduction in reactive oxygen species levels. The results from this study clarify our understandings on the effect of hyaluronan on stem cells and provide important insights into the effect of distinct supplementation methods used during cell therapies.

Permeabilized muscle fibers (pfi) are widely used to assess mitochondrial (mt) respiratory function in skeletal muscle of various models in different physiological and pathological conditions. Facing the numerous data available for mt-respiration from the literature, it remains challenging to determine what the right values are for a specific respiratory protocol. Moreover, mt-respiration values are highly dependent on pfi preparation, which required good technical skills. In the frame of COST Action MITOEAGLE, one of the objectives of WG2 is the generation of reference values for mitochondrial respirometry in permeabilized skeletal muscle sample preparations. The idea is that new researchers in the field follow a reference protocol and check if their values are in an acceptable range. This approach could serve to test researchers&#39; technical skills and therefore determine if they are proficient enough to perform their own experiments with confidence.

Permeabilized muscle fibers (pfi) are widely used to assess mitochondrial (mt) respiratory function in skeletal muscle of various models in different physiological and pathological conditions. Facing the numerous data available for mt-respiration from the literature, it remains challenging to determine what the right values are for a specific respiratory protocol. Moreover, mt-respiration values are highly dependent on pfi preparation, which required good technical skills. In the frame of COST Action MITOEAGLE, one of the objectives of WG2 is the generation of reference values for mitochondrial respirometry in permeabilized skeletal muscle sample preparations. The idea is that new researchers in the field follow a reference protocol and check if their values are in an acceptable range. This approach could serve to test researchers&#39; technical skills and therefore determine if they are proficient enough to perform their own experiments with confidence.

Background/Aims: Obesity is a risk factor associated with cardiometabolic complications. Recently, we reported that miRNA-22 deletion attenuated high-fat diet-induced adiposity and prevented dyslipidemia without affecting cardiac hypertrophy in male mice. In this study, we examined the impact of miRNA-22 in obesogenic diet-induced cardiovascular and metabolic disorders in females. Methods: Wild type (WT) and miRNA-22 knockout (miRNA-22 KO) females were fed a control or an obesogenic diet. Body weight gain, adiposity, glucose tolerance, insulin tolerance, and plasma levels of total cholesterol and triglycerides were measured. Cardiac and white adipose tissue remodeling was assessed by histological analyses. Echocardiography was used to evaluate cardiac function and morphology. RNA-sequencing analysis was employed to characterize mRNA expression profiles in female hearts. Results: Loss of miRNA-22 attenuated body weight gain, adiposity, and prevented obesogenic diet-induced insulin re...

Permeabilized muscle fibers (pfi) are widely used to assess mitochondrial (mt) respiratory function in skeletal muscle of various models in different physiological and pathological conditions. Facing the numerous data available for mt-respiration from the literature, it remains challenging to determine what the right values are for a specific respiratory protocol. Moreover, mt-respiration values are highly dependent on pfi preparation, which required good technical skills. In the frame of COST Action MITOEAGLE, one of the objectives of WG2 is the generation of reference values for mitochondrial respirometry in permeabilized skeletal muscle sample preparations. The idea is that new researchers in the field follow a reference protocol and check if their values are in an acceptable range. This approach could serve to test researchers&#39; technical skills and therefore determine if they are proficient enough to perform their own experiments with confidence.

Permeabilized muscle fibers (pfi) are widely used to assess mitochondrial (mt) respiratory function in skeletal muscle of various models in different physiological and pathological conditions. Facing the numerous data available for mt-respiration from the literature, it remains challenging to determine what the right values are for a specific respiratory protocol. Moreover, mt-respiration values are highly dependent on pfi preparation, which required good technical skills. In the frame of COST Action MITOEAGLE, one of the objectives of WG2 is the generation of reference values for mitochondrial respirometry in permeabilized skeletal muscle sample preparations. The idea is that new researchers in the field follow a reference protocol and check if their values are in an acceptable range. This approach could serve to test researchers&#39; technical skills and therefore determine if they are proficient enough to perform their own experiments with confidence.

Metabolic flexibility is an essential characteristic of eukaryotic cells in order to adapt to physiological and environmental changes. Especially in mammalian cells, the metabolic switch from mitochondrial respiration to aerobic glycolysis provides flexibility to sustain cellular energy in pathophysiological conditions. For example, attenuation of mitochondrial respiration and/or metabolic shifts to glycolysis result in a metabolic rewiring that provide beneficial effects in neurodegenerative processes. Ferroptosis, a non-apoptotic form of cell death triggered by an impaired redox balance is gaining attention in the field of neurodegeneration. We showed recently that activation of small-conductance calcium-activated K+ (SK) channels modulated mitochondrial respiration and protected neuronal cells from oxidative death. Here, we investigated whether SK channel activation with CyPPA induces a glycolytic shift thereby increasing resilience of neuronal cells against ferroptosis, induced ...

An integrative evaluation of oxidative metabolism was carried out in 9 healthy young men (age, 24.1 Ϯ 1.7 yr mean Ϯ SD) before (CTRL) and after a 10-day horizontal bed rest carried out in normoxia (N-BR) or hypoxia (H-BR, FI O 2 ϭ 0.147). H-BR was designed to simulate planetary habitats. Pulmonary O 2 uptake (V O2) and vastus lateralis fractional O2 extraction (changes in deoxygenated hemoglobinϩmyoglobin concentration, ⌬[deoxy(HbϩMb)] evaluated using near-infrared spectroscopy) were evaluated in normoxia and during an incremental cycle ergometer (CE) and one-leg knee extension (KE) exercise (aimed at reducing cardiovascular constraints to oxidative function). Mitochondrial respiration was evaluated ex vivo by high-resolution respirometry in permeabilized vastus lateralis fibers. During CE V O2peak and ⌬[deoxy(HbϩMb)]peak were lower (P Ͻ 0.05) after both N-BR and H-BR than during CTRL; during KE the variables were lower after N-BR but not after H-BR. During CE the overshoot of ⌬[deoxy(HbϩMb)] during constant work rate exercise was greater in N-BR and H-BR than CTRL, whereas during KE a significant difference vs. CTRL was observed only after N-BR. Maximal mitochondrial respiration determined ex vivo was not affected by either intervention. In N-BR, a significant impairment of oxidative metabolism occurred downstream of central cardiovascular O 2 delivery and upstream of mitochondrial function, possibly at the level of the intramuscular matching between O 2 supply and utilization and peripheral O2 diffusion. Superposition of hypoxia on bed rest did not aggravate, and partially reversed, the impairment of muscle oxidative function in vivo induced by bed rest. The effects of longer exposures will have to be determined. muscle inactivity; microgravity; hypoxia; mitochondrial respiration; oxidative function NEW & NOTEWORTHY Superposition of 10 days of hypoxia on profound physical inactivity (bed rest) did not aggravate (and partially attenuated) impairment of oxidative function in vivo induced by bed rest alone. The main site(s) of impairment are presumably downstream of cardiovascular function but upstream of mito

Purpose The purpose of this study was to investigate, in obese adults, changes in body composition, physical capacities, fat oxidation and ex vivo mitochondrial respiration induced by a 3-month either moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT); afterwards, the patients were followed for four months. Methods Thirty-two patients (mean age 39 years; mean body mass index [BMI] 36 kg•m −2) participated in this study attending ~ 34 sessions of training. At baseline (PRE), at the end of the program (POST) and after follow-up, body composition, peak O 2 uptake (V′O 2 peak) and fat oxidation rate were measured. Vastus lateralis biopsies for the evaluation of mitochondrial respiration were performed only at PRE and POST. Results At POST, body mass (BM) and fat mass (FM) decreased (− 6 and − 14%, respectively, P < 0.05) in MICT and HIIT; V′O 2 peak increased in both groups (+ 6 and + 16%, respectively, P < 0.05). Maximal fat oxidation rate increased only after HIIT (P < 0.001). Maximal ADP-stimulated mitochondrial respiration normalized by citrate synthase increased (P < 0.05) by 67% and 36% in MICT and HIIT, respectively, without significant difference. After follow-up, BM and FM were still lower (− 4 and − 20%, respectively, P < 0.050) compared with baseline in both groups. Only after HIIT, V′O 2 peak (+ 8%) and maximal fat oxidation rate were still higher (P < 0.05). Conclusions HIIT was more effective in improving and maintaining V'O 2 peak and fat oxidation. These results may be relevant for an appropriate prescription of training programs designed to optimize aerobic fitness in obese subjects.

Metabolic flexibility is the ability of a cell to adapt its metabolism to changes in its surrounding environment. Such adaptability, combined with apoptosis resistance provides cancer cells with a survival advantage. Mitochondrial voltage-dependent anion channel 1 (VDAC1) has been defined as a metabolic checkpoint at the crossroad of these two processes. Here, we show that the hypoxia-induced cleaved form of VDAC1 (VDAC1-ΔC) is implicated in both the up-regulation of glycolysis and the mitochondrial respiration. We demonstrate that VDAC1-ΔC, due to the loss of the putative phosphorylation site at serine 215, concomitantly with the loss of interaction with tubulin and microtubules, reprograms the cell to utilize more metabolites, favoring cell growth in hypoxic microenvironment. We further found that VDAC1-ΔC represses ciliogenesis and thus participates in ciliopathy, a group of genetic disorders involving dysfunctional primary cilium. Cancer, although not representing a ciliopathy, ...

A simple and reproducible method for the treatment of Arabidopsis thaliana leaves with rotenone is presented. Rosette leaves were incubated with rotenone and Triton X-100 for at least 15 h. Treated leaves showed increased expression of COX19 and BCS1a, two genes known to be induced in Arabidopsis cell cultures after rotenone treatment. Moreover, rotenone/Triton X-100 incubated leaves presented an inhibition of oxygen uptake. The simplicity of the procedure shows this methodology useful for studying the effect of the addition of rotenone to a photosynthetic tissue in situ.

Recently, we showed that generation of tumours in syngeneic mice by cells devoid of mitochondrial (mt) DNA (ρ0 cells) is linked to the acquisition of the host mtDNA. However, the mechanism of mtDNA movement between cells remains unresolved. To determine whether the transfer of mtDNA involves whole mitochondria, we injected B16ρ0 mouse melanoma cells into syngeneic C57BL/6Nsu9-DsRed2 mice that express red fluorescent protein in their mitochondria. We document that mtDNA is acquired by transfer of whole mitochondria from the host animal, leading to normalisation of mitochondrial respiration. Additionally, knockdown of key mitochondrial complex I (NDUFV1) and complex II (SDHC) subunits by shRNA in B16ρ0 cells abolished or significantly retarded their ability to form tumours. Collectively, these results show that intact mitochondria with their mtDNA payload are transferred in the developing tumour, and provide functional evidence for an essential role of oxidative phosphorylation in can...

Diabetes and obesity are prevalent in westernized countries. In both conditions, excessive fatty acid uptake by cardiomyocytes induces cardiac lipotoxicity, an important mechanism contributing to diabetic cardiomyopathy. This study investigated the effect of calpain disruption on cardiac lipotoxicity. Cardiac-specific capns1 knockout mice and their wild-type littermates (male, age of 4weeks) were fed a high fat diet (HFD) or normal diet for 20weeks. HFD increased body weight, altered blood lipid profiles and impaired glucose tolerance comparably in both capns1 knockout mice and their wild-type littermates. Calpain activity, cardiomyocyte cross-sectional areas, collagen deposition and triglyceride were significantly increased in HFD-fed mouse hearts, and these were accompanied by myocardial dysfunction and up-regulation of hypertrophic and fibrotic collagen genes as well as pro-inflammatory cytokines. These effects of HFD were attenuated by disruption of calpain in capns1 knockout mi...

Recently, we showed that generation of tumours in syngeneic mice by cells devoid of mitochondrial (mt) DNA (ρ0 cells) is linked to the acquisition of the host mtDNA. However, the mechanism of mtDNA movement between cells remains unresolved. To determine whether the transfer of mtDNA involves whole mitochondria, we injected B16ρ0 mouse melanoma cells into syngeneic C57BL/6Nsu9-DsRed2 mice that express red fluorescent protein in their mitochondria. We document that mtDNA is acquired by transfer of whole mitochondria from the host animal, leading to normalisation of mitochondrial respiration. Additionally, knockdown of key mitochondrial complex I (NDUFV1) and complex II (SDHC) subunits by shRNA in B16ρ0 cells abolished or significantly retarded their ability to form tumours. Collectively, these results show that intact mitochondria with their mtDNA payload are transferred in the developing tumour, and provide functional evidence for an essential role of oxidative phosphorylation in can...

Altered metabolism is an important feature of many epileptic syndromes but has not been reported in Dravet syndrome (DS), a catastrophic childhood epilepsy associated with mutations in a voltage-activated sodium channel, Nav1.1 (SCN1A). To address this, we developed novel methodology to assess real-time changes in bioenergetics in zebrafish larvae between 4 and 6 d postfertilization (dpf). Baseline and 4-aminopyridine (4-AP) stimulated glycolytic flux and mitochondrial respiration were simultaneously assessed using a Seahorse Biosciences extracellular flux analyzer. Scn1Lab mutant zebrafish showed a decrease in baseline glycolytic rate and oxygen consumption rate (OCR) compared to controls. A ketogenic diet formulation rescued mutant zebrafish metabolism to control levels. Increasing neuronal excitability with 4-AP resulted in an immediate increase in glycolytic rates in wild-type zebrafish, whereas mitochondrial OCR increased slightly and quickly recovered to baseline values. In co...

Purpose: It is well established that high-load resistance exercise (HLRE) can stimulate myofibrillar accretion. Additionally, recent studies suggest that HLRE can also stimulate mitochondrial biogenesis and respiratory function. However, in several clinical situations, the use of resistance exercise with high loading may not constitute a viable approach. Low-load blood flow restricted resistance exercise (BFRRE) has emerged as a timeeffective low-load alternative to stimulate myofibrillar accretion. It is unknown if BFRRE can also stimulate mitochondrial biogenesis and respiratory function. If so, BFRRE could provide a feasible strategy to stimulate muscle metabolic health. Methods: To study this, 34 healthy previously untrained individuals (24 ± 3 years) participated in BFRRE, HLRE, or non-exercise control intervention (CON) 3 times per week for 6 weeks. Skeletal muscle biopsies were collected; (1) before and after the 6-week intervention period to assess mitochondrial biogenesis and respiratory function and; (2) during recovery from single-bout exercise to assess myocellular signaling events involved in transcriptional regulation of mitochondrial biogenesis. During the 6-week intervention period, deuterium oxide (D 2 O) was continuously administered to the participants to label newly synthesized skeletal muscle mitochondrial proteins. Mitochondrial respiratory function was assessed in permeabilized muscle fibers with high-resolution respirometry. Mitochondrial content was assessed with a citrate synthase activity assay. Myocellular signaling was assessed with immunoblotting. Results: Mitochondrial protein synthesis rate was higher with BFRRE (1.19%/day) and HLRE (1.15%/day) compared to CON (0.92%/day) (P < 0.05) but similar between exercise groups. Mitochondrial respiratory function increased to similar degree with both exercise regimens and did not change with CON. For instance, coupled respiration supported by convergent electron flow from complex I and II increased 38% with BFRRE and 24% with HLRE (P < 0.01). Training did not alter citrate synthase activity compared to CON. BFRRE and HLRE elicited similar myocellular signaling responses.

Nos travaux de recherche menes dans l’ischemie cerebrale neonatale ont evalue l’effet de la Ciclosporine A sur la reduction du volume lesionnel, mais aussi sur le fonctionnement du metabolisme mitochondrial. Nous avons egalement etudie l’effet du postconditionnement ischemique et les consequences hemodynamiques de la reperfusion. Le pore de permeabilite membranaire mPTP s’ouvre au cours de l’ischemie neonatale. La CsA, inhibiteur de la Cyclophiline D freine l’ouverture du pore mPTP, ameliore la capacite de recapture du calcium par la mitochondrie, la respiration mitochondriale, et limite les effets inflammatoires de l’ischemie. Neanmoins, la CsA ne reduit pas le volume des lesions cerebrales. Nous avons pu montrer que la Cyclophiline D et le pore mPTP etaient bien deux acteurs majeurs dans la constitution des lesions induites par la reperfusion dans l’ischemie cerebrale focale neonatale. Le postconditionnement ischemique ne permet pas de reduire les volumes des lesions. Nous avons m...

Neuroinflammation is characterized by activation of microglial cells, followed by production of nitric oxide (NO), which may have different outcomes on neurogenesis, favoring or inhibiting this process. In the present study, we investigated how the inflammatory mediator NO can affect proliferation of neural stem cells (NSCs), and explored possible mechanisms underlying this effect. We investigated which mechanisms are involved in the regulation of NSC proliferation following treatment with an inflammatory stimulus (lipopolysaccharide plus IFN-γ), using a culture system of subventricular zone (SVZ)-derived NSCs mixed with microglia cells obtained from wild-type mice (iNOS +/+) or from iNOS knockout mice (iNOS −/−). We found an impairment of NSC cell proliferation in iNOS +/+ mixed cultures, which was not observed in iNOS −/− mixed cultures. Furthermore, the increased release of NO by activated iNOS +/+ microglial cells decreased the activation of the ERK/MAPK signaling pathway, which was concomitant with an enhanced nitration of the EGF receptor. Preventing nitrogen reactive species formation with MnTBAP, a scavenger of peroxynitrite (ONOO −), or using the ONOO − degradation catalyst FeTMPyP, cell proliferation and ERK signaling were restored to basal levels in iNOS +/+ mixed cultures. Moreover, exposure to the NO donor NOC-18 (100 μM), for 48 h, inhibited SVZ-derived NSC proliferation. Regarding the antiproliferative effect of NO, we found that NOC-18 caused the impairment of signaling through the ERK/MAPK pathway, which may be related to increased nitration of the EGF receptor in NSC. Using MnTBAP nitration was prevented, maintaining ERK signaling, rescuing NSC proliferation. We show that NO from inflammatory origin leads to a decreased function of the EGF receptor, which compromised proliferation of NSC. We also demonstrated that NO-mediated nitration of the EGF receptor caused a decrease in its phosphorylation, thus preventing regular proliferation signaling through the ERK/MAPK pathway.

Mitochondria have been considered for long time as important determinants of cell aging because of their role in the production of reactive oxygen species. In this study we investigated the impact of mitochondrial metabolism and biology as determinants of successful aging in primary cultures of fibroblasts isolated from the skin of long living individuals (LLI) (about 100 years old) compared with those from young (about 27 years old) and old (about 75 years old) subjects. We observed that fibroblasts from LLI displayed significantly lower complex I-driven ATP synthesis and higher production of H2O2 in comparison with old subjects. Despite these changes, bioenergetics of these cells appeared to operate normally. This lack of functional consequences was likely due to a compensatory phenomenon at the level of mitochondria, which displayed a maintained supercomplexes organization and an increased mass. This appears to be due to a decreased mitophagy, induced by hyperfused, elongated mit...

Background: The C452F mutation in the mitochondrial fission protein Drp1 leads to heart failure through an unknown mechanism. Results: C452F impairs Drp1 disassembly, leading to impaired mitophagy, failed bioenergetics, and inflammation. Conclusion: Drp1-mediated mitochondrial fission is essential for normal cardiac function. Significance: Mutations in mitochondrial quality control proteins are a likely cause of human cardiomyopathy. We have reported previously that a missense mutation in the mitochondrial fission gene Dynamin-related protein 1 (Drp1) underlies the Python mouse model of monogenic dilated cardiomyopathy. The aim of this study was to investigate the consequences of the C452F mutation on Drp1 protein function and to define the cellular sequelae leading to heart failure in the Python monogenic dilated cardiomyopathy model. We found that the C452F mutation increased Drp1 GTPase activity. The mutation also conferred resistance to oligomer disassembly by guanine nucleotides and high ionic strength solutions. In a mouse embryonic fibroblast model, Drp1 C452F cells exhibited abnormal mitochondrial morphology and defective mitophagy. Mitochondria in C452F mouse embryonic fibroblasts were depolarized and had reduced calcium uptake with impaired ATP production by oxidative phosphorylation. In the Python heart, we found a corresponding progressive decline in oxidative phosphorylation with age and activation of sterile inflammation. As a corollary, enhancing autophagy by exposure to a prolonged low-protein diet improved cardiac function in Python mice. In conclusion, failure of Drp1 disassembly impairs mitophagy, leading to a downstream cascade of mitochondrial depolarization, aberrant calcium handling, impaired ATP synthesis, and activation of sterile myocardial inflammation, resulting in heart failure.

Mitochondria have been considered for long time as important determinants of cell aging because of their role in the production of reactive oxygen species. In this study we investigated the impact of mitochondrial metabolism and biology as determinants of successful aging in primary cultures of fibroblasts isolated from the skin of long living individuals (LLI) (about 100 years old) compared with those from young (about 27 years old) and old (about 75 years old) subjects. We observed that fibroblasts from LLI displayed significantly lower complex I-driven ATP synthesis and higher production of H2O2 in comparison with old subjects. Despite these changes, bioenergetics of these cells appeared to operate normally. This lack of functional consequences was likely due to a compensatory phenomenon at the level of mitochondria, which displayed a maintained supercomplexes organization and an increased mass. This appears to be due to a decreased mitophagy, induced by hyperfused, elongated mit...

Background: It has been suggested that oxygen (O 2) diffusion could be favored in water enriched in O 2 by a new electrolytic process because of O 2 trapping in water superstructures (clathrates), which could reduce the local pressure/content relationships for O 2 and facilitate O 2 diffusion along PO 2 gradients. Materials and methods: Mitochondrial respiration was compared in situ in saponin-skinned fibers isolated from the soleus muscles of Wistar rats, in solution enriched in O 2 by injection or the electrolytic process 1) at an O 2 concentration decreasing from 240 µmol/L to 10 µmol/L (132 mmHg to 5 mmHg), with glutamate-malate or N, N, N′, N′-tetramethyl-p-phenylenediamine dihydrochloride (TMPD)-ascorbate (with antimycin A) as substrates; and 2) at increasing adenosine diphosphate (ADP) concentration with glutamate-malate as substrate. Results: As expected, maximal respiration decreased with O 2 concentration and, when compared to glutamate-malate, the apparent Km O 2 of mitochondria for O 2 was significantly lower with TMPD-ascorbate with both waters. However, when compared to the water enriched in O 2 by injection, the Km O 2 was significantly lower with both electron donors in water enriched in O 2 by electrolysis. This was not associated with any increase in the sensitivity of mitochondria to ADP; no significant difference was observed for the Km ADP between the two waters. Conclusion: In this experiment, a higher affinity of the mitochondria for O 2 was observed in water enriched in O 2 by electrolysis than by injection. This observation is consistent with the hypothesis that O 2 diffusion can be facilitated in water enriched in O 2 by the electrolytic process.

Petasin (1), a natural product found in plants of the genus Petasites, has beneficial medicinal effects, such as antimigraine and antiallergy activities. However, whether or not 1 modulates metabolic diseases is unknown. In this study, the effects of 1 on AMP-activated protein kinase (AMPK), which is considered a pharmacological target for treating metabolic diseases, are described. It was found that an extract of Petasites japonicus produces an increase in the phosphorylation of AMPK in vitro, and the main active compound 1 was isolated. When this compound was administered orally to mice, activation of AMPK in the liver, skeletal muscle, and adipose tissue was observed. Moreover, pretreatment with 1 enhanced glucose tolerance following the administration of a glucose solution to normal mice. The mechanism by which 1 activates AMPK was subsequently investigated, and an increased intracellular AMP/ATP ratio in the cultured cells treated with 1 occurred. In addition, treatment with petasin inhibited mitochondrial respiratory chain complex I. Taken together, the present results indicated that 1 modulates glucose metabolism and activates AMPK through the inhibition of mitochondrial respiration. The preclinical data suggested that petasin (1) could be useful for the treatment of metabolic diseases in humans.

Nucleoside diphosphate kinase (NDPK/Nm23), responsible
for intracellular di- and triphosphonucleoside homeostasis,
plays multiple roles in cellular energetics, signaling, proliferation,
differentiation and tumor invasion. The only human
NDPK with a mitochondrial targeting sequence is NDPK-D, the
NME4 gene product, which is a peripheral protein of mitochondrial
membranes. Subfractionation of rat liver and HEK 293 cell
mitochondria revealed that NDPK-D is essentially bound to the
inner membrane. Surface plasmon resonance analysis of the
interaction using recombinant NDPK-D and model liposomes
showed that NDPK-D interacts electrostatically with anionic
phospholipids, with highest affinity observed for cardiolipin.
Mutation of the central arginine (Arg-90) in a surface-exposed
basic RRK motif unique to NDPK-D strongly reduced interaction
with anionic phospholipids. Due to its symmetrical hexameric
structure, NDPK-D was able to cross-link anionic phospholipid-
containing liposomes, suggesting that NDPK-D could
promote intermembrane contacts. Latency assays with isolated
mitochondria and antibody binding to mitoplasts indicated a
dual orientation for NDPK-D. In HeLa cells, stable expression of
wild type but not of the R90D mutant led to membrane-bound
enzyme in vivo. Respiration was significantly stimulated by the
NDPK substrate TDP in mitochondria containing wild-type
NDPK-D, but not in those expressing the R90D mutant, which is
catalytically equally active. This indicates local ADP regeneration
in the mitochondrial intermembrane space and a tight
functional coupling of NDPK-D with oxidative phosphorylation
that depends on its membrane-bound state.

Acknowledgments : Ivan Dinh -> No co-author

A simple and reproducible method for the treatment of Arabidopsis thaliana leaves with rotenone is presented. Rosette leaves were incubated with rotenone and Triton X-100 for at least 15 h. Treated leaves showed increased expression of COX19 and BCS1a, two genes known to be induced in Arabidopsis cell cultures after rotenone treatment. Moreover, rotenone/Triton X-100 incubated leaves presented an inhibition of oxygen uptake. The simplicity of the procedure shows this methodology useful for studying the effect of the addition of rotenone to a photosynthetic tissue in situ.

Unlike cardiac and skeletal muscle, little is known about vascular smooth muscle mitochondrial respiration. Therefore, the present study examined mitochondrial respiratory rates in smooth muscle of healthy human feed arteries and compared with that of healthy cardiac and skeletal muscles. Cardiac, skeletal, and smooth muscles were harvested from a total of 22 subjects (53 ± 6 yr), and mitochondrial respiration was assessed in permeabilized fibers. Complex I + II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac to skeletal to smooth muscles (54 ± 1, 39 ± 4, and 15 ± 1 pmol·s−1·mg−1, P &lt; 0.05, respectively). Citrate synthase (CS) activity, an index of mitochondrial density, also fell progressively from cardiac to skeletal to smooth muscles (222 ± 13, 115 ± 2, and 48 ± 2 μmol·g−1·min−1, P &lt; 0.05, respectively). Thus, when respiration rates were normalized by CS (respiration per mitochondrial content), oxidative phosphorylation ...

Polycystic ovary syndrome (PCOS) is a common endocrinopathy that is associated with an adverse metabolic profile including reduced postprandial thermogenesis. Although abnormalities in adipose tissue function have been widely reported in women with PCOS, less is known about direct effects of androgen on white and, particularly, brown adipocytes. The purpose of this study was to investigate the effect of the nonaromatizable androgen dihydrotestosterone (DHT) on (1) lipid accumulation and expression of adipogenic markers in immortalized mouse brown adipose cell lines (IMBATs), (2) mitochondrial respiration in IMBATs, (3) mitochondrial DNA content and gene expression, (4) expression of brown adipose tissue (BAT) markers and thermogenic activation. In addition, we profiled the relative levels of 38 adipokines secreted from BAT explants and looked at androgen effects on adipokine gene expression in both IMBATs and immortalized mouse white adipose (IMWATs) cell lines. Androgen treatment i...

Carbon monoxide (CO), a product of heme degradation by heme oxygenases, plays an important role in vascular homeostasis. Recent evidence indicates that mitochondria are among a number of molecular targets that mediate the cellular actions of CO. In the present study we characterized the effects of CO released from CORM-401 on mitochondrial respiration and glycolysis in intact human endothelial cells using electron paramagnetic resonance (EPR) oximetry and the Seahorse XF technology. We found that CORM-401 (10-100μM) induced a persistent increase in the oxygen consumption rate (OCR) that was accompanied by inhibition of glycolysis (extracellular acidification rate, ECAR) and a decrease in ATP-turnover. Furthermore, CORM-401 increased proton leak, diminished mitochondrial reserve capacity and enhanced non-mitochondrial respiration. Inactive CORM-401 (iCORM-401) neither induced mitochondrial uncoupling nor inhibited glycolysis, supporting a direct role of CO in the endothelial metaboli...

Sexual dimorphism is apparent in humans, however, to date no studies have investigated mitochondrial function focusing on intrinsic mitochondrial respiration (i.e., mitochondrial respiration for a given amount of mitochondrial protein) and mitochondrial oxygen affinity (p50 mito) in relation to biological sex in human. A skeletal muscle biopsy was donated by nine active women, and ten men matched for maximal oxygen consumption (VO 2max) and by nine endurance trained men. Intrinsic mitochondrial respiration, assessed in isolated mitochondria, was higher in women compared to men when activating complex I (CI P) and complex I+II (CI+II P) (p < 0.05), and was similar to trained men (CI P , p = 0.053; CI+II P , p = 0.066). Proton leak and p50 mito were higher in women compared to men independent of VO 2max. In conclusion, significant novel differences in mitochondrial oxidative function, intrinsic mitochondrial respiration and p50 mito exist between women and men. These findings may represent an adaptation in the oxygen cascade in women to optimize muscle oxygen uptake to compensate for a lower oxygen delivery during exercise.

Recent evidence highlights that the cancer cell energy requirements vary greatly from normal cells and that cancer cells exhibit different metabolic phenotypes with variable participation of both glycolysis and oxidative phosphorylation. NADH-ubiquinone oxidoreductase (Complex I) is the largest complex of the mitochondrial electron transport chain and contributes about 40% of the proton motive force required for mitochondrial ATP synthesis. In addition, Complex I plays an essential role in biosynthesis and redox control during proliferation, resistance to cell death, and metastasis of cancer cells. Although knowledge about the structure and assembly of Complex I is increasing, information about the role of Complex I subunits in tumorigenesis is scarce and contradictory. Several small molecule inhibitors of Complex I have been described as selective anticancer agents; however, pharmacologic and genetic interventions on Complex I have also shown pro-tumorigenic actions, involving diff...

Permeabilized muscle fibers (pfi) are widely used to assess mitochondrial (mt) respiratory function in skeletal muscle of various models in different physiological and pathological conditions. Facing the numerous data available for mt-respiration from the literature, it remains challenging to determine what the right values are for a specific respiratory protocol. Moreover, mt-respiration values are highly dependent on pfi preparation, which required good technical skills. In the frame of COST Action MITOEAGLE, one of the objectives of WG2 is the generation of reference values for mitochondrial respirometry in permeabilized skeletal muscle sample preparations. The idea is that new researchers in the field follow a reference protocol and check if their values are in an acceptable range. This approach could serve to test researchers&#39; technical skills and therefore determine if they are proficient enough to perform their own experiments with confidence.

Given the potential for myocardial stem cell transplantation as a promising treatment for heart failure, numerous clinical trials have been conducted and its usefulness has been clearly confirmed. However, the low rate of engraftment of transplanted cells has become a clinical problem, and this needs to be improved in the case of transplanting cells to the heart. To address this issue, we report on attempts to prepare mitochondria-activated stem cells (MITO cells) for use in transplantation. MITO cells, which is cardiac progenitor cells (CPCs) activated by the mitochondrial delivery of resveratrol with an anti-oxidant and mitochondrial activation effects were successfully prepared using a mitochondrial targeting nanocarrier (MITO-Porter). The purpose of this study was to validate the therapeutic effect of cell transplantation by the MITO cells using a mouse model of myocardial ischemia–reperfusion. Mouse CPCs were used as transplanted cells. The transplantation of CPCs and MITO cell...

Microglia fulfill important immunological functions in the brain by responding to pathological stresses and modulating their activities according to pro-or anti-inflammatory stimuli. Recent evidence indicates that changes in metabolism accompany the switch in microglia activation state, favoring glycolysis over oxidative phosphorylation when cells exhibit a pro-inflammatory phenotype. Carbon monoxide (CO), a byproduct of heme breakdown by heme oxygenase, exerts anti-inflammatory action and affects mitochondrial function in cells and tissues. In the present study, we analyzed the metabolic profile of BV2 and primary mouse microglia exposed to the CO-releasing molecules CORM-401 and CORM-A1 and investigated whether CO affects the metabolic adaptation of cells to the inflammatory stimulus lipopolysaccharide (LPS). Microglia respiration and glycolysis were measured using an Extracellular Flux Analyzer to provide a real-time bioenergetic assessment, and biochemical parameters were evaluated to define the metabolic status of the cells under normal or inflammatory conditions. We show that CO prevents LPS-induced depression of microglia respiration and reduction in ATP levels while altering the early expression of inflammatory markers, suggesting the metabolic changes induced by CO are associated with control of inflammation. CO alone affects microglia respiration depending on the concentration, as low levels increase oxygen consumption while higher amounts inhibit respiration. Increased oxygen consumption was attributed to an uncoupling activity observed in cells, at the molecular level (respiratory complex activities) and during challenge with LPS. Thus, application of CO is a potential countermeasure to reverse the metabolic changes that occur during microglia inflammation and in turn modulate their inflammatory profile.

Carbon monoxide (CO)-releasing molecules (CO-RMs) are intensively studied to provide cytoprotective and anti-inflammatory effects of CO in inflammatory conditions including intestinal inflammation. The water-soluble CORM-A1 reduced apoptosis and NADPH oxidase (NOX)-derived reactive oxygen species (ROS) induced by tumor necrosis factor (TNF)-α/cycloheximide (CHX) in mouse MODE-K intestinal epithelial cells (IECs), without influencing TNF-α/CHX-induced mitochondrial superoxide anion (O •− 2). The aim of the present study in the same model was to comparatively investigate the influence of lipid-soluble CORM-2 and water-soluble CORM-401, shown in vitro to release more CO under oxidative conditions. CORM-2 abolished TNF-α/CHX-induced total cellular ROS whereas CORM-401 partially reduced it, both partially reducing TNF-α/CHXinduced cell death. Only CORM-2 increased mitochondrial O •− 2 production after 2 h of incubation. CORM-2 reduced TNF-α/CHX-, rotenone-and antimycin-A-induced mitochondrial O •− 2 production; CORM-401 only reduced the effect of antimycin-A. Co-treatment with CORM-401 during 1 h exposure to H 2 O 2 reduced H 2 O 2 (7.5 mM)induced ROS production and cell death, whereas CORM-2 did not. The study illustrates the importance of the chemical characteristics of different CORMs. The lipid solubility of CORM-2 might contribute to its interference with TNF-α/CHX-induced mitochondrial ROS signaling, at least in mouse IECs. CORM-401 is more effective than other CORMs under H 2 O 2-induced oxidative stress conditions.