Control of adenine nucleotide metabolism in hepatic mitochondria from rats with ethanol-induced fatty liver

Cellular Bioenergetics: Experimental Evidence for Alcohol-induced Adaptations

At-risk alcohol use is associated with multisystemic effects and end-organ injury, and significantly contributes to global health burden. Several alcohol-mediated mechanisms have been identified, with bioenergetic maladaptation gaining credence as an underlying pathophysiological mechanism contributing to cellular injury. This evidence-based review focuses on the current knowledge of alcohol-induced bioenergetic adaptations in metabolically active tissues: liver, cardiac and skeletal muscle, pancreas, and brain. Alcohol metabolism itself significantly interferes with bioenergetic pathways in tissues, particularly the liver. Alcohol decreases states of respiration in the electron transport chain, and activity and expression of respiratory complexes, with a net effect to decrease ATP content. In addition, alcohol dysregulates major metabolic pathways, including glycolysis, the tricarboxylic acid cycle, and fatty acid oxidation. These bioenergetic alterations are influenced by alcohol-mediated changes in mitochondrial morphology, biogenesis, and dynamics. The review highlights similarities and differences in bioenergetic adaptations according to tissue type, pattern of (acute vs. chronic) alcohol use, and energy substrate availability. The compromised bioenergetics synergizes with other critical pathophysiological mechanisms, including increased oxidative stress and accelerates cellular dysfunction, promoting senescence, programmed cell death, and end-organ injury.

Mitochondrial damage, cytotoxicity and apoptosis in iron-potentiated alcoholic liver fibrosis: amelioration by taurine

Taurine effectively prevents ischemia-induced apoptosis in the cardiomyocytes and hypothalamic nuclei. The present study explores the influence of taurine on mitochondrial damage, oxidative stress and apoptosis in experimental liver fibrosis. Male albino Wistar rats were divided into six groups and maintained for a period of 60 days as follows: Group I, control; Group II, ethanol treatment [6 g/(kg/day)]; Group III, fibrosis induced by ethanol and iron (0.5% w/w); Group IV, ethanol + iron + taurine (2% w/v); Group V, ethanol + taurine treatment and Group VI, control + taurine treatment. Hepatocytes isolated from ethanol plus iron-treated rats showed decreased cell viability and redox ratio, increased reactive oxygen species formation, lipid peroxidation, DNA fragmentation, and formation of apoptotic bodies. Liver mitochondria showed increased susceptibility to swell, diminished activities of mitochondrial respiratory chain complexes and antioxidants. Taurine administration to fibrotic rats restored mitochondrial function, reduced reactive oxygen species formation, prevented DNA damage, and apoptosis. Thus taurine might contribute to the amelioration of the disease process.

Novel interactions of mitochondria and reactive oxygen/nitrogen species in alcohol mediated liver disease

Mitochondrial dysfunction is known to be a contributing factor to a number of diseases including chronic alcohol induced liver injury. While there is a detailed understanding of the metabolic pathways and proteins of the liver mitochondrion, little is known regarding how changes in the mitochondrial proteome may contribute to the development of hepatic pathologies. Emerging evidence indicates that reactive oxygen and nitrogen species disrupt mitochondrial function through post-translational modifications to the mitochondrial proteome. Indeed, various new affinity labeling reagents are available to test the hypothesis that post-translational modification of proteins by reactive species contributes to mitochondrial dysfunction and alcoholic fatty liver disease. Specialized proteomic techniques are also now available, which allow for identification of defects in the assembly of multi-protein complexes in mitochondria and the resolution of the highly hydrophobic proteins of the inner membrane. In this review knowledge gained from the study of changes to the mitochondrial proteome in alcoholic hepatotoxicity will be described and placed into a mechanistic framework to increase understanding of the role of mitochondrial dysfunction in liver disease.

Alcohol-induced oxidative stress

Alcohol-induced oxidative stress is linked to the metabolism of ethanol involving both microsomal and mitochondrial systems. Ethanol metabolism is directly involved in the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). These form an environment favourable to oxidative stress. Ethanol treatment results in the depletion of GSH levels and decreases antioxidant activity. It elevates malondialdehyde (MDA), hydroxyethyl radical (HER), and hydroxynonenal (HNE) protein adducts. These cause the modification of all biological structures and consequently result in serious malfunction of cells and tissues.

Ethanol self-administration and alterations in the livers of the cynomolgus monkey, Macaca fascicularis

BACKGROUND

Most of the studies of alcoholic liver disease use models in which animals undergo involuntary administration of high amounts of ethanol and consume diets that are often high in polyunsaturated fatty acids. The objectives of this study were (1) to evaluate whether cynomolgus monkeys (Macaca fascicularis) drinking ethanol voluntarily and consuming a diet with moderate amounts of lipid would demonstrate any indices of alcoholic liver disease past the fatty liver stage and (2) to determine whether these alterations were accompanied by oxidative stress.

METHODS

Six adult male and 6 adult female cynomolgus monkeys were allowed to consume ethanol voluntarily for 18 to 19 months. Additional monkeys were maintained on the same consumption protocol, but were not provided with ethanol. During the course of the study, liver biopsy samples were monitored for lipid deposition and inflammation, serum for levels of liver enzymes, and urine for concentrations of the isoprostane (IsoP) metabolite, 2,3-dinor-5,6-dihydro-15-F(2t)-IsoP, a biomarker for oxidative stress. Liver mitochondria were monitored for respiratory control and liver for concentrations of neutral lipids, adenine nucleotides, esterified F(2) isoprostanes, oxidized proteins, 4-hydroxynonenal (HNE)-protein adducts, and protein levels of cytochrome P-450 2E1 and 3A4.

RESULTS

Ethanol consumption ranged from 0.9 to 4.05 g/kg/d over the period of the study. Serum levels of aspartate amino transferase were elevated in heavy-consuming animals compared with those in ethanol-naïve or moderate drinkers. Many of the ethanol consumers developed fatty liver and most showed loci of inflammation. Both hepatic energy charge and phosphorylation potential were decreased and NADH-linked respiration was slightly, but significantly depressed in coupled mitochondria as a result of heavy ethanol consumption. The urinary concentrations of 2,3-dinor-5,6-dihydro-15-F(2t)-IsoP increased as high as 33-fold over that observed in ethanol-abstinent animals. Liver cytochrome P-450 2E1 concentrations increased in ethanol consumers, but there were no ethanol-elicited increases in hepatic concentrations of the esterified F(2) isoprostanes, oxidized proteins, or HNE-protein adducts.

CONCLUSION

Our studies show that cynomolgus monkeys undergoing voluntary ethanol consumption for 1.5 years exhibit many of the features observed in the early stages of human alcoholic liver disease. Ethanol-elicited fatty liver, inflammation, and elevated serum aspartate amino transferase were evident with a diet that contained modest amounts of polyunsaturated lipids. The dramatic increases in urinary IsoP demonstrated that the animals were being subjected to significant oxidative stress that correlated with their level of ethanol consumption.

S-adenosylmethionine prevents chronic alcohol-induced mitochondrial dysfunction in the rat liver

An early event that occurs in response to alcohol consumption is mitochondrial dysfunction, which is evident in changes to the mitochondrial proteome, respiration defects, and mitochondrial DNA (mtDNA) damage. S-adenosylmethionine (SAM) has emerged as a potential therapeutic for treating alcoholic liver disease through mechanisms that appear to involve decreases in oxidative stress and proinflammatory cytokine production as well as the alleviation of steatosis. Because mitochondria are a source of reactive oxygen/nitrogen species and a target for oxidative damage, we tested the hypothesis that SAM treatment during alcohol exposure preserves organelle function. Mitochondria were isolated from livers of rats fed control and ethanol diets with and without SAM for 5 wk. Alcohol feeding caused a significant decrease in state 3 respiration and the respiratory control ratio, whereas SAM administration prevented these alcohol-mediated defects and preserved hepatic SAM levels. SAM treatment prevented alcohol-associated increases in mitochondrial superoxide production, mtDNA damage, and inducible nitric oxide synthase induction, without a significant lessening of steatosis. Accompanying these indexes of oxidant damage, SAM prevented alcohol-mediated losses in cytochrome c oxidase subunits as shown using blue native PAGE proteomics and immunoblot analysis, which resulted in partial preservation of complex IV activity. SAM treatment attenuated the upregulation of the mitochondrial stress chaperone prohibitin. Although SAM supplementation did not alleviate steatosis by itself, SAM prevented several key alcohol-mediated defects to the mitochondria genome and proteome that contribute to the bioenergetic defect in the liver after alcohol consumption. These findings reveal new molecular targets through which SAM may work to alleviate one critical component of alcohol-induced liver injury: mitochondria dysfunction.

Identification of oxidized mitochondrial proteins in alcohol-exposed human hepatoma cells and mouse liver

Heavy alcohol consumption can damage various cells and organs partly through production of reactive oxygen species (ROS) and mitochondrial dysfunction. Treatment with antioxidants can significantly reduce the degree of damage. Despite well established roles of ROS in alcohol-induced cell injury, the proteins that are selectively oxidized by ROS are poorly characterized. We hypothesized that certain cysteinyl residues of target proteins are oxidized by ROS upon alcohol exposure, and these modified proteins may play roles in mitochondrial dysfunction. A targeted proteomics approach utilizing biotin-N-maleimide (biotin-NM) as a specific probe to label oxidized cysteinyl residues was employed to investigate which mitochondrial proteins are modified during and after alcohol exposure. Human hepatoma HepG2 cells with transduced CYP2E1 (E47 cells) were used as a model to generate ROS through CYP2E1-mediated ethanol metabolism. Following exposure to 100 mM ethanol for 4 and 8 h, the biotin-NM-labeled oxidized proteins were purified with agarose coupled to either streptavidin or monoclonal antibody against biotin. The purified proteins were resolved by two-dimensional gel electrophoresis and protein spots that displayed differential abundances were excised from the gel, in-gel digested with trypsin and analyzed for identity utilizing either matrix-assisted laser desorption-time of flight mass spectrometry or microcapillary reversed-phase liquid chromatography-tandem mass spectrometry. The results demonstrate that heat shock protein 60, protein disulfide isomerase, mitochondrial aldehyde dehydrogenases, prohibitin, and other proteins were oxidized after alcohol exposure. The identity of some of the proteins purified with streptavidin-agarose was also confirmed by immunoblot analyses using the specific antibody to each target protein. This method was also used to identify oxidized mitochondrial proteins in the alcohol-fed mouse liver. These results suggest that exposure to ethanol causes oxidation of various mitochondrial proteins that may negatively affect their function and contribute to alcohol-induced mitochondrial dysfunction and cellular injury.

Oxidative modification of hepatic mitochondria protein thiols: effect of chronic alcohol consumption

Redox modification of mitochondrial proteins is thought to play a key role in regulating cellular function, although direct evidence to support this hypothesis is limited. Using an in vivo model of mitochondrial redox stress, ethanol hepatotoxicity, the modification of mitochondrial protein thiols was examined using a proteomics approach. Specific labeling of reduced thiols in the mitochondrion from the livers of control and ethanol-fed rats was achieved by using the thiol reactive compound (4-iodobutyl)triphenylphosphonium (IBTP). This molecule selectively accumulates in the organelle and can be used to identify thiol-containing proteins. Mitochondrial proteins that have been modified are identified by decreased labeling with IBTP using two-dimensional SDS-PAGE followed by immunoblotting with an antibody directed against the triphenylphosphonium moiety of the IBTP molecule. Analyses of these data showed a significant decrease in IBTP labeling of thiols present in specific mitochondria matrix proteins from ethanol-fed rats compared with their corresponding controls. These proteins were identified as the low-K(m) aldehyde dehydrogenase and glucose-regulated protein 78. The decrease in IBTP labeling in aldehyde dehydrogenase was accompanied by a decrease in specific activity of the enzyme. These data demonstrate that mitochondrial protein thiol modification is associated with chronic alcohol intake and might contribute to the pathophysiology associated with hepatic injury. Taken together, we have developed a protocol to chemically tag and select thiol-modified proteins that will greatly enhance efforts to establish posttranslational redox modification of mitochondrial protein in in vivo models of oxidative or nitrosative stress.

Modification of the mitochondrial proteome in response to the stress of ethanol-dependent hepatotoxicity

Mitochondria are particularly susceptible to increased formation of reactive oxygen and nitrogen species in the cell that can occur in response to pathological and xenobiotic stimuli. Proteomics can give insights into both mechanism of pathology and adaptation to stress. Herein we report the use of proteomics to evaluate alterations in the levels of mitochondrial proteins following chronic ethanol exposure in an animal model. Forty-three proteins showed differential expression, 13 increased and 30 decreased, as a consequence of chronic ethanol. Of these proteins, 25 were not previously known to be affected by chronic ethanol emphasizing the power of proteomic approaches in revealing global responses to stress. Both nuclear and mitochondrially encoded gene products of the oxidative phosphorylation complexes in mitochondria from ethanol-fed rats were decreased suggesting an assembly defect in this integrated metabolic pathway. Moreover mtDNA damage was increased by ethanol demonstrating that the effects of ethanol consumption extend beyond the proteome to encompass mtDNA. Taken together, we have demonstrated that chronic ethanol consumption extends to a modification of the mitochondrial proteome far broader than realized previously. These data also suggest that the response of mitochondria to stress may not involve non-discriminate changes in the proteome but is restricted to those metabolic pathways that have a direct role in a specific pathology.

Correlation between adenosine triphosphate content and apoptosis in liver of rats treated with alcohol

BACKGROUND

Chronic alcohol consumption depresses adenosine triphosphate (ATP) synthesis and induces mitochondrial DNA (Mt-DNA) deletion. ATP content in cells may play a critical role in inducing cell death, apoptosis, or necrosis. However, it is unknown which type of cell death occurs in alcoholic liver disease. In this study, the deletions of hepatic Mt-DNA, hepatic ATP content, and the number of single-stranded DNA (ss-DNA) of hepatocytes in rats treated with ethanol were determined to elucidate the relationship among Mt-DNA deletion, ATP synthesis, and/or hepatic apoptosis.

METHODS

Sixteen male Wistar rats were fed with a liquid diet containing 36% ethanol (E group) or liquid diet without ethanol (C group) for 5 weeks. Hepatic ATP content was measured and the deletions of Mt-DNA encoding complexes I, IV, and V were determined in fresh liver tissue, and ss-DNA was stained in paraffin sections.

RESULTS

Fatty change was observed in the E group, but not in the C group. Hepatic ATP content in the E group was 0.44 micromol/g of liver, which was significantly lower than that in the C group (0.84 micromol/g of liver). However, no deletion of Mt-DNA encoding complexes I, IV, and V was detected in either the E or the C group. ss-DNA staining was clearly observed in the nuclei of hepatocytes in both groups. The number of ss-DNA-positive hepatocytes in the E group was 5.6 +/- 1.8/10,000 hepatocytes, which was significantly less than that in the C group: 20.6 +/- 4.8/10,000 hepatocytes. There was a positive correlation between hepatic ATP contents and the number of ss-DNA-positive cells.

CONCLUSIONS

The results suggest that mitochondrial function, at least in part ATP synthesis, was depressed before the damage of Mt-DNA by chronic ethanol consumption. Chronic ethanol consumption may not be responsible for the apoptosis of hepatocytes.

Chronic alcohol consumption increases the sensitivity of rat liver mitochondrial respiration to inhibition by nitric oxide

Chronic alcohol consumption is a well-known risk factor for hepatic injury, and mitochondrial damage plays a significant role in this process. Nitric oxide (NO) is an important modulator of mitochondrial function and is known to inhibit mitochondrial respiration. However, the impact of chronic alcohol consumption on NO-dependent control of liver mitochondrial function is unknown. This study examines the effect of alcohol exposure on liver mitochondria in a rat model and explores the interaction of NO and mitochondrial respiration in this context. Mitochondria were isolated from the liver of both control and ethanol-fed rats after 5 to 6 weeks of alcohol consumption. Mitochondria isolated from ethanol-treated rats showed a significant decrease in state 3 respiration and respiratory control ratio that was accompanied by an increased sensitivity to NO-dependent inhibition of respiration. In conclusion, we show that chronic alcohol consumption leads to increased sensitivity to the inhibition of respiration by NO. We propose that this results in a greater vulnerability to hypoxia and the development of alcohol-induced hepatotoxicity.

A review of the role of reactive oxygen and nitrogen species in alcohol-induced mitochondrial dysfunction

Our understanding of the mechanisms involved in the development of alcohol-induced liver disease has increased substantially in recent years. Specifically, reactive oxygen and nitrogen species have been identified as key components in initiating and possibly sustaining the pathogenic pathways responsible for the progression from alcohol-induced fatty liver to alcoholic hepatitis and cirrhosis. Ethanol has been demonstrated to increase the production of reactive oxygen and nitrogen species and decrease several antioxidant mechanisms in liver. However, the relative contribution of the proposed sites of ethanol-induced reactive species production within the liver is still not clear. It has been proposed that chronic ethanol-elicited alterations in mitochondria structure and function might result in increased production of reactive species at the level of the mitochondrion in liver from ethanol consumers. This in turn might result in oxidative modification and inactivation of mitochondrial macromolecules, thereby contributing further to mitochondrial dysfunction and a loss in hepatic energy conservation. Moreover, ethanol-related increases in reactive species may shift the balance between pro- and anti-apoptotic factors such that there is activation of the mitochondrial permeability transition, which would lead to increased cell death in the liver after chronic alcohol consumption. This article will examine the critical role of these reactive species in ethanol-induced liver injury with specific emphasis on how chronic ethanol-associated alterations to mitochondria influence the production of reactive oxygen and nitrogen species and how their production may disrupt hepatic energy conservation in the chronic alcohol abuser.

Emerging techniques in biomedical research and their application to alcohol toxicity

This article represents the proceedings of a symposium at the 2002 RSA-ISBRA Meeting in San Francisco. The chairs were Vinood B. Patel and Victor R. Preedy. The presentations were (1) Macromolecular structural analysis, by Vinood B. Patel; (2) Profiling and imaging of proteins in tissue sections using mass spectrometry as a discovery tool in biological research, by Pierre Chaurand and Richard M. Caprioli; (3) The use of SELDI ProteinChip trade mark arrays, by Brian M. Austen, Emma R. Frears, Francesca Manca, and Huw Davies; (4) DNA hybridization array technologies, by Kent E. Vrana; and (5) Adeno- and adeno-associated viral mediated gene transfer approaches for alcoholic liver disease, by Michael Wheeler. Concluding remarks were by Victor R. Preedy.

Altered hepatic mitochondrial ribosome structure following chronic ethanol consumption

Chronic ethanol consumption decreases the synthesis of all 13 polypeptides encoded by the hepatic mitochondrial genome. This alteration in mitochondrial protein synthesis is due to modifications in mitochondrial ribosomes. In the current study, the nature of these alterations was investigated by determining some of the hydrodynamic properties, namely sedimentation coefficient, shape, and mass of mitochondrial ribosomes. The effect of ethanol consumption on the capacity for mitochondrial ribosomes to translate proteins was also determined using an in vitro Poly (U) assay system. Rats were fed the Lieber-DeCarli diet for 31 days with ethanol as 36% of total calories. The sedimentation coefficient, measured by sedimentation velocity analyses, was slightly, but significantly lower in ethanol mitochondrial ribosomes (53.2 +/- 0.5S) when compared with pair-fed controls (54.1 +/- 0.5S) (P = 0.04). Mitochondrial ribosomes from ethanol-fed animals also had a greater tendency to dissociate into subunits. The diffusion coefficient, determined by dynamic light scattering, was lower in mitochondrial ribosomes from ethanol-fed rats than pair-fed controls and this indicated a significantly greater diameter for ethanol ribosomes (42.1 +/- 0.2 nm) than for preparations from pair-fed controls (39.1 +/- 0.5 nm; P = 0.008). These alterations to ethanol mitochondrial ribosomes occurred despite no change in molecular mass, which suggested a significant ethanol-related shape change in the ribosomes. The translation capacity of mitochondrial ribosome preparations from ethanol-fed animals was markedly reduced due to dissociation of the monosome into light and heavy subunits. In summary, these observations demonstrate that chronic ethanol consumption causes significant structural and functional alterations to mitochondrial ribosomes. The loss in ribosome function leads to impaired mitochondrial polypeptide synthesis and is an example of a pathology giving rise to an alteration in the mitochondrial ribosome structure.

Contribution of mitochondria to oxidative stress associated with alcoholic liver disease

The importance of oxidative stress in the development of alcoholic liver disease has long been appreciated. The mechanism by which ethanol triggers an increase in reactive oxygen species in the liver is complex, however, recent findings suggest that the mitochondrion may contribute significantly to the overall increase in oxidant levels in hepatocytes exposed to ethanol acutely or chronically. This review is focused on observations which indicate that the ability of ethanol to increase mitochondrial reactive oxygen species production is linked to its metabolism via oxidative processes and/or ethanol-related alterations to the mitochondrial electron transport chain. Furthermore, the capacity of ethanol-elicited increases in reactive oxygen species to oxidatively modify and inactivate mitochondrial proteins is highlighted as a mechanism by which ethanol might further disrupt the structure and function of mitochondria.

Effects of chronic ethanol feeding on the protein composition of mitochondrial ribosomes

Chronic ethanol feeding has been shown to decrease the number of functionally active mitochondrial ribosomes by 55%. In this work, 55S mitochondrial ribosomes were isolated from rat liver and their constitutive proteins characterized by two-dimensional polyacrylamide gel electrophoresis and quantified by densitometry. A total of 86 proteins were found to be associated with the mitochondrial ribosome. This compares with 70 isolated from cytoplasmic ribosomes. In addition, mitochondrial ribosomal proteins were found to be significantly less basic than their cytoplasmic counterparts. Chronic ethanol feeding was found to significantly decrease the levels of a number of constitutive proteins of the mitochondrial ribosome when compared to those isolated from pair-fed controls. Sucrose density gradient analyses revealed a significant decrease in the number of intact 55S ribosomes. It is suggested that ethanol-elicited alterations in specific constitutive proteins of the mitochondrial ribosome may lead to impaired assembly of the monosome and that this may result in lower levels of those displaying functional activity.

Chronic ethanol ingestion increases efficiency of oxidative phosphorylation in rat liver mitochondria

The efficiency of oxidative phosphorylation was compared between rats chronically fed with ethanol and controls. (i) Results showed that the liver mitochondria state 4 respiratory rate was strongly inhibited, while the corresponding proton-motive force was not affected; (ii) the cytochrome oxidase content and activity were decreased and (iii) the oxidative-phosphorylation yield was increased in the ethanol exposed group. Furthermore, oxidative phosphorylation at coupling site II was not affected by ethanol. Cytochrome oxidase inhibition by sodium-azide mimicked the effects of ethanol intoxication in control mitochondria. This indicates that the decrease in cytochrome oxidase activity induced by ethanol intoxication directly increases the efficiency of oxidative phosphorylation.

Acute and chronic ethanol increases reactive oxygen species generation and decreases viability in fresh, isolated rat hepatocytes

Although reactive oxygen species (ROS) have been implicated in the etiology of alcohol-induced liver disease, neither their relative contribution to cell death nor the cellular mechanisms mediating their formation are known. The purpose of this study was to test the hypothesis that acute and chronic ethanol exposure enhances the mitochondrial generation of ROS in fresh, isolated hepatocytes. Acute ethanol exposure stimulated ROS production, increased the cellular NADH/NAD+ ratio, and decreased hepatocyte viability slightly, which was prevented by pretreatment with 4-methylpyrazole (4-MP), an inhibitor of alcohol dehydrogenase. Similarly, xylitol, an NADH-generating compound, enhanced hepatocyte ROS production and decreased viability. Incubation with pyruvate, an NADH-oxidizing compound, and cyanamide, an inhibitor of aldehyde dehydrogenase, significantly decreased ROS levels in acute ethanol-treated hepatocytes. Chronic ethanol consumption produced a sixfold increase in hepatocyte ROS production compared with levels measured in controls. Hepatocytes from ethanol-fed rats were less viable compared with controls, e.g., viability was 68% +/- 2% (ethanol) versus 83% +/- 1% (control) after 60 minutes of incubation. Antimycin A increased ROS production and decreased cell viability; however, the toxic effect of antimycin A was more pronounced in ethanol-fed hepatocytes. These results suggest that acute and chronic ethanol exposure exacerbates mitochondrial ROS production, contributing to cell death.

Effect of chronic ethanol consumption on respiratory and glycolytic activities of rat periportal and perivenous hepatocytes

Previous studies (Ivester et al., Arch. Biochem. Biophys. 322, 14-21, 1995) have established that periportal and perivenous hepatocytes isolated from ethanol-fed rats demonstrate lower ATP concentrations than those in control preparations when the cells are maintained at very low oxygen tension. In the present investigation, experiments were implemented with periportal and perivenous hepatocytes to determine the effects of chronic ethanol consumption on cellular respiratory and glycolytic activities, since both contribute to maintenance of the energy state of the liver cell. Both periportal and perivenous hepatocytes from ethanol-fed rats demonstrated significantly increased, rather than decreased, respiratory activity when monitored with oxygen concentrations ranging from 16 to 140 microM. Whole liver hepatocytes from control and ethanol-fed animals demonstrated equivalent oxygen utilization, however. Glycolytic activity, monitored by lactate + pyruvate concentrations obtained after both anaerobic and aerobic incubation protocols, was decreased in both cell types from ethanol-fed animals. The glycogen concentrations in freshly isolated periportal and perivenous hepatocytes were also decreased eight- and sevenfold, respectively, as compared with control preparations. Incubation under anaerobic conditions resulted in almost complete depletion of glycogen in both cell types. These observations suggest the possibility that the decreased energy state observed in hepatocytes from ethanol-fed animals is related to a depression in anaerobic glycolysis due to depletion of the endogenous substrate, glycogen.

Effects of alcohol on energy metabolism and body weight regulation: is alcohol a risk factor for obesity?

Some studies have suggested that drinking in moderation may be beneficial for health, but many of these studies do not address body weight. Evidence suggests that consuming moderate amounts of alcohol is a risk factor for obesity, which is a risk factor for several adverse health outcomes. Recommendations regarding alcohol intake thus should take into account a variety of factors, including baseline body weight, location of body fat, and overall diet.

Differential effects of ethanol consumption on synthesis of cytoplasmic and mitochondrial encoded subunits of the ATP synthase

The relative concentrations of several subunits of the mitochondrial F0.F1-ATP synthase were determined in mitochondria and submitochondrial particles prepared from the livers of ethanol-fed and control rats. The polypeptides were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis and the stained gels were analyzed by densitometry for the relative concentrations of the ATP synthase subunits. A significant decrease in the relative concentration of the mitochondrial gene product, ATPase subunit 8, was observed in mitochondria and submitochondrial particles from ethanol-fed animals. The relative concentration of the other mitochondrial encoded ATPase subunit, ATPase 6, was also depressed, as confirmed in submitochondrial particles. In contrast, there were no significant ethanol-related depressions in subunits alpha, beta, and OSCP of the F0.F1 or the adenine nucleotide carrier in intact mitochondria. These results demonstrate that ethanol consumption causes a decrease in the content of mitochondrial synthesized subunits 6 and 8 whereas no effect is exerted on the concentrations of nuclear gene products of the ATP synthase complex. Likewise, the adenine nucleotide transporter, also a nuclear gene product, is unaffected by ethanol consumption.

Mitochondrial respiratory activity and superoxide radical generation in the liver, brain and heart after chronic ethanol intake

Functional characteristics of mitochondria isolated from liver, brain and heart were studied in ethanol-fed rats using ethanol administration in drinking water as a model of moderate alcohol intoxication. Our results show a slight decrease in liver cytochrome aa3 content, the mitochondrial alteration which is most consistently observed during chronic ethanol feeding. In liver and heart mitochondria, ethanol consumption led to an increase in state 3 respiration with NAD(+)-linked substrates, whereas no changes were apparent in respiration rates with succinate as substrate. However a decrease was found in state 3 respiration with succinate in brain mitochondria isolated from ethanol-fed rats. Submitochondrial particles (SMP) were used to study the superoxide radical (O2-.) production at the level of antimycin-inhibited regions of the respiratory chain. It appears that there is no clear correlation between ethanol effects on respiration and O2-. production. Whereas O2-. generation remained unchanged in heart mitochondria, an elevation of O2-. generation was observed in brain mitochondria, and in contrast, the rate of O2-. production was decreased in liver mitochondria of the ethanol-group in comparison to the control-group. Our findings support a tissue specificity for the toxic effects of ethanol towards the mitochondria and indicate that mitochondrial free radical mechanisms are involved in ethanol-induced toxicity in the brain.

Mitochondrial glutathione depletion in alcoholic liver disease

Alcoholic liver disease (ALD) is one the most serious consequences of chronic alcohol abuse. Liver cirrhosis, the culmination of the illness, is one of the leading causes of death in Western countries. Mitochondria are a target of ethanol intoxication mainly due to the toxic effects of acetaldehyde, a byproduct of ethanol metabolism. Morphological and functional changes in mitochondria are one of the key hallmarks of chronic ethanol exposure in both chronic alcoholics and experimental models of alcoholism. The functional changes observed in mitochondria from ethanol-treated animals are translated in an overall decrease in ATP levels resulting from a lower rate of ATP synthesis as a consequence of impaired processing at the translational level of some components of oxidative phosphorylation encoded by mitochondrial DNA genome. Mitochondrial glutathione (GSH) plays a critical role in the maintenance of cell functions and viability and in mitochondrial physiology by metabolism of oxygen free radicals generated in the respiratory chain. GSH in mitochondria originates from cytosol by a transport system which translocates GSH into the matrix. This transport system is impaired in chronic ethanol-fed rats, which translates in a selective and significant depletion of the mitochondrial GSH content resulting in the development of an increased susceptibility to oxidant stress. Using the intragastric infusion model of experimental ALD in rats, the profound and selective mitochondrial GSH depletion precedes the onset of alcoholic liver disease, mitochondrial lipid peroxidation, and progression of liver damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in mitochondrial function and morphology in chronic liver disease: pathogenesis and potential for therapeutic intervention

Studies assessing mitochondrial function and structure in livers from humans or experimental animals with chronic liver disease, including liver cirrhosis, revealed a variety of alterations in comparison with normal subjects or control animals. Depending on the etiology of chronic liver disease, the function of the electron transport chain and/or ATP synthesis was found to be impaired, leading to decreased oxidative metabolism of various substrates and to impaired recovery of the hepatic energy state after a metabolic insult. Changes in mitochondrial structure include megamitochondria with reduced cristae, dilatation of mitochondrial cristae and crystalloid inclusions in the mitochondrial matrix. The most important strategies to maintain an adequate mitochondrial function per liver are mitochondrial proliferation and increases in the activity of critical enzymes or in the content of cofactors per mitochondrion. Possibilities to assess hepatic mitochondrial function and to treat mitochondrial dysfunction in patients with chronic liver disease are discussed.

Hepatic mitochondrial glutathione depletion and progression of experimental alcoholic liver disease in rats

Long-term ethanol feeding has been shown to selectively reduce hepatic mitochondrial glutathione content by impairing mitochondrial uptake of this thiol. In this study, we assessed the role of this defect in evolution of alcoholic liver disease by examining the mitochondrial glutathione pool and lipid peroxidation during progression of experimental alcoholic liver disease to centrilobular liver necrosis and fibrosis. Male Wistar rats were intragastrically infused with a high-fat diet plus ethanol for 3, 6 or 16 wk (the duration that resulted in induction of liver steatosis, necrosis and fibrosis, respectively). During this feeding period, the cytosolic pool of glutathione remained unchanged in the ethanol-fed animals compared with that in pair-fed controls. In contrast, the mitochondrial pool of glutathione selectively and progressively decreased in rats infused with ethanol for 3, 6 or 16 wk, by 39%, 61% and 85%, respectively. Renal mitochondrial glutathione level remained unaffected throughout the experiment. Serum ALT levels increased significantly in the ethanol-fed rats at 6 wk and remained elevated at 16 wk. In the mitochondria with severely depleted glutathione levels at 16 wk, enhanced lipid peroxidation was evidenced by increased malondialdehyde levels. Thus a progressive and selective depletion of mitochondrial glutathione is demonstrated in the liver in this experimental model of alcoholic liver disease and associated with mitochondrial lipid peroxidation and progression of liver damage.

Biochemistry of alcoholic liver disease

The biochemistry of alcohol liver disease as it relates to clinical medicine and experimental alcohol liver disease is presented. Clinical features are emphasized in the diagnosis of alcohol liver disease, particularly as it relates to staging the disease and predictors of prognosis. Currently, it is true that the biochemical diagnosis of alcohol liver disease is at best very limited in terms of the sensitivity tests and specificity of the test. It is particularly difficult to detect alcohol liver disease biochemically in the early stages when steatohepatitis is not severe. Consequently, 50% of the patients have already developed cirrhosis at the time they are diagnosed clinically. In this review indicators of malnutrition are emphasized because they have the strongest implications regarding survival during the acute hospitalization stage of the disease. They are also the best indicators of response to therapy during the recovery phase. With respect to experimental work on the pathogenesis of alcohol liver disease, it appears that necrosis is due to the inability to increase blood flow to compensate for increased oxygen utilization. The hypothesis that mitochondrial damage is the cause of liver cell damage is regarded as less important in the pathogenesis of necrosis. The shift in the redox state during alcohol metabolism accounts for the fatty change noted in the central lobular area of the liver in animals fed alcohol. Apparently, there is strong experimental evidence that highly reactive intermediates are important in the pathogenesis of liver damage due to the induction of the isozyme cytochrome P450 IIE1 by alcohol ingestion. This mechanism is enhanced by a diet high in polyunsaturated fatty acids.

Alcohol, liver, and nutrition

Until two decades ago, dietary deficiencies were considered to be the major reason why alcoholics developed liver disease. As the overall nutrition of the population improved, more emphasis was placed on secondary malnutrition. Direct hepatotoxic effects of ethanol were also established, some of which were linked to redox changes produced by reduced nicotinamide adenine dinucleotide (NADH) generated via the alcohol dehydrogenase (ADH) pathway. It was also determined that ethanol can be oxidized by a microsomal ethanol oxidizing system (MEOS) involving cytochrome P-450: the newly discovered ethanol-inducible cytochrome P-450 (P-450IIE1) contributes to ethanol metabolism, tolerance, energy wastage (with associated weight loss), and the selective hepatic perivenular toxicity of various xenobiotics. P-450 induction also explains depletion (and enhanced toxicity) of nutritional factors such as vitamin A. Even at the early fatty-liver stage, alcoholics commonly have a very low hepatic concentration of vitamin A. Ethanol administration in animals was found to depress hepatic levels of vitamin A, even when administered with diets containing large amounts of the vitamin, reflecting, in part, accelerated microsomal degradation through newly discovered microsomal pathways of retinol metabolism, inducible by either ethanol or drug administration. The hepatic depletion of vitamin A was strikingly exacerbated when ethanol and other drugs were given together, mimicking a common clinical occurrence. Hepatic retinoid depletion was found to be associated with lysosomal lesions and decreased detoxification of chemical carcinogens. To alleviate these adverse effects, as well as to correct problems of night blindness and sexual inadequacies, the alcoholic patient should be provided with vitamin A supplementation. Such therapy, however, is complicated by the fact that in excessive amounts vitamin A is hepatotoxic, an effect exacerbated by long-term ethanol consumption. This results in striking morphologic and functional alterations of the mitochondria with leakage of mitochondrial enzymes, hepatic necrosis, and fibrosis. Thus, treatment with vitamin A and other nutritional factors (such as proteins) is beneficial but must take into account a narrowed therapeutic window in alcoholics who have increased needs for such nutrients, but also display an enhanced susceptibility to their adverse effects. Massive doses of choline also exerted some toxic effects and failed to prevent the development of alcoholic cirrhosis. Acetaldehyde (the metabolite produced from ethanol by either ADH or MEOS) impairs hepatic oxygen utilization and forms protein adducts, resulting in antibody production, enzyme inactivation, and decreased DNA repair. It also enhances pyridoxine and perhaps folate degradation and stimulates collagen production by the vitamin A storing cells (lipocytes) and myofibroblasts.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of chronic ethanol consumption on hepatic mitochondrial transcription and translation

Liver mitochondria from ethanol-fed rats display an impaired ability for protein synthesis in vitro. Studies were conducted to explore the possible mechanisms which might account for this impaired capacity of ethanol mitochondria for protein synthesis. The present studies did not demonstrate any significant ethanol-induced lesion in mitochondrial nucleic acid metabolism in organelles isolated from ethanol-fed rats for any of the parameters investigated (mtDNA content, steady-state mtRNA concentration, mtRNA polymerase activity, concentration of specific mRNAs and rRNAs, mtRNA processing). An investigation of ribosome function in isolated mitochondria demonstrated significant decreases in the number of active ribosomes (55% fewer) in mitochondria from ethanol-fed rats. Initiation of protein synthesis was also significantly depressed (46%) in ethanol mitochondria. In addition, the yield of ribosomal particles from ethanol mitochondria was decreased 32% as compared to the yield of ribosomal particles from control mitochondria. However, isolated ribosomes from ethanol mitochondria were determined to be fully functional in a poly(U)-directed phenylalanine polymerization system. Soluble translation factors from ethanol mitochondria were also found to support full activity of control ribosomes in a poly(U)-directed phenylalanine polymerization system. These results suggest strongly that the ethanol-induced depression of mitochondrial protein synthesis is due to a decrease in the number of competent ribosomes in hepatic mitochondria from chronically ethanol-fed rats.

Effects of chronic ethanol consumption on the synthesis of polypeptides encoded by the hepatic mitochondrial genome

Liver mitochondria from rats fed ethanol chronically demonstrate an impaired ability to incorporate [35S]methionine into polypeptide products in vitro. This ethanol-induced effect on mitochondrial translation in vitro could not be attributed to significant differences in the methionine precursor pool sizes of ethanol and control mitochondria or to the acute effects of residual ethanol. The observed reduction of radiolabeled methionine incorporation into mitochondrial gene products of ethanol mitochondria in vitro reflects a decrease in the synthesis of all the mitochondrial gene products. However, the percentage of total radiolabel incorporated into each gene product is unaffected by ethanol, suggesting an ethanol-induced coordinate depression of mitochondrial protein synthesis. Moreover, SDS-PAGE and densitometry of submitochondrial particles from ethanol-fed and control rats demonstrated that the steady-state concentration of each of the mitochondrial gene products is decreased in ethanol-fed rats. This reduction of the steady-state concentration of the mitochondrial gene products may be related to the observed depressions of oxidative phosphorylation activities associated with hepatic mitochondria from ethanol-fed rats.

Comparison of effects of long-term ethanol consumption on the heart and liver of the rat

Alterations in heart and liver metabolism were determined periodically in Sprague-Dawley rats pair-fed a liquid diet (ethanol, 36% of calories) for times as long as 1 year. In liver mitochondria the rate of ATP synthesis was lowered significantly after ethanol administration for 1 month and longer feeding periods. In liver microsomes from ethanol-fed animals, ethanol oxidation and aniline hydroxylation increased 1.5- and 3.5-fold, respectively, after 1 month and remained elevated at the longer feeding intervals. Electron microscopic analyses of heart left ventricles revealed no alterations from ethanol consumption for 1 month. Alterations including disrupted mitochondrial cristae, dilatation of sarcoplasmic reticulum, and widening of the intercalated discs were observed after 6.5-month feeding periods. Myocardial concentrations of creatine, creatine phosphate, ATP, ADP, and Pi remained constant even after ethanol consumption for 9 months. After a 12-month feeding period slight changes in cardiac mitochondrial energy-linked properties were observed which were not as pronounced as those occurring in liver mitochondria. The activity and oligomycin sensitivity of the ATPase were not altered in cardiac mitochondria, whereas in liver preparations significant alterations in these properties of the ATPase were apparent after ethanol consumption for 1 month and the longer feeding periods. These observations suggest that the liver responds more quickly and dramatically to chronic ethanol consumption than does the heart.

Effects of moderate chronic ethanol consumption on rat liver mitochondrial functions

The biochemical consequences of moderate chronic ethanol ingestion has been scarcely investigated in spite of the fact that most of the human population drinks ethanol on a moderate basis. This paper describes some metabolic effects produced by moderate ethanol consumption. The substitution of drinking water in rats for a 10% ethanol solution during 4 weeks resulted in: a) a decrease of blood urea and citrulline synthesis in liver mitochondria; b) a slight inhibition in state 3 and state 4 respiration either with glutamate-malate as substrates or succinate as substrate; c) no change in ADP/O ratio with succinate but slight increase with glutamate-malate; d) a reduction of the cytochrome oxidase activity and cytochromes a+a3 content; e) a 42% increase in the succinate dehydrogenase activity and a small but constant increase in the Vmax (no change in the Km) of the adenine nucleotide translocase activity in liver mitochondria. These results show that even moderate, but continuous ethanol ingestion, produces metabolic responses that must be carefully evaluated to define health risk in larger human groups.

Hepatic adenosine in rats fed ethanol: effect of acute hyperoxia or hypoxia

The level of adenosine was measured in monthly biopsied livers from rats fed ethanol and a high fat/low protein diet in order to test a hypothesis that hepatic adenosine is increased due to enhanced breakdown of adenine nucleotides in which ATP and total adenylate pool were decreased by chronic ethanol feeding. The ethanol-fed rats showed a significantly higher average level of adenosine compared to the pair-fed controls. When investigated monthly, however, adenosine in ethanol-fed rats increased only after the decrease in ATP had stabilized and AMP remained unchanged, indicating that these changes were not temporarily related. The average percentage of change in adenosine after acute hyperoxia or hypoxia were variable both in ethanol-fed and pair-fed rats. There was a tendency for a positive correlation between the percentage of change of adenosine and AMP after hyperoxia regardless of ethanol feeding. A negative correlation between the percentage of change of adenosine and energy charge, and a positive correlation between the percentage of change of adenosine and AMP were seen after hypoxia regardless of ethanol feeding. Adenosine levels changed rapidly in response to changes in systemic of pO2 in both the ethanol-fed and control rats, indicating that the liver maintained its normal response to the changes in energy state. The results indicate that chronic ethanol feeding does increase the level of adenosine in the liver and that this level remains responsive to acute changes in pO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Control of state 3 respiration in liver mitochondria from rats subjected to chronic ethanol consumption

Male Sprague-Dawley rats were pair-fed a liquid diet containing 36% of calories as ethanol for at least 31 days. Mitochondria were isolated from the livers and assayed for state 3, state 4 and uncoupled respiration at all three coupling sites. Assay conditions were established that maximized state 3 respiration with each substrate while maintaining a high respiratory control ratio. In mitochondria from ethanol-fed animals, state 3 respiratory rates were decreased at all three coupling sites. The decreased state 3 rate observed at site III was still significantly higher than the state 3 rates observed at site II in mitochondria from either ethanol-fed or control animals. Moreover, the maximal (FCCP-uncoupled) rates with succinate and alpha-ketoglutarate were the same in mitochondria from ethanol-fed and control animals, whereas with glutamate-malate as substrate it was lowered 23% by chronic ethanol consumption. To investigate the role of cytochrome oxidase in modulating the respiratory rate with site I and site II substrates, the effects of cyanide on state 3 and FCCP-uncoupled respiration were determined. When the mitochondria were uncoupled there was no decrease in the rate of succinate oxidation until the rates of ascorbate and succinate oxidation became equivalent. Conversely, parallel inhibition of ascorbate, succinate and glutamate-malate state 3 respiratory rates were observed at all concentrations (1-50 microM) of cyanide utilized. These observations suggest strongly that in coupled mitochondria ethanol-elicited decreases in cytochrome oxidase activity depress the state 3 respiratory rates with site I and II substrates.

The effect of chronic ethanol consumption on the lipids in liver mitochondria

The ethanol-related alterations in hepatic mitochondrial phospholipids are primarily changes in acyl chain composition. There are no alterations in the unesterified cholesterol content in the mitochondrion, as measured by the cholesterol-phospholipid ratio. Moreover, the distribution of mitochondrial phospholipids are not changed as a result of chronic ethanol consumption. There was a significant ethanol-related decrease (18%) in the phospholipid-protein ratio in mitochondria from rats maintained on a low-fat diet, which was not observed in studies where animals were fed diets containing a higher proportion of lipid. This effect of dietary composition on the phospholipid-protein ratio was also paralleled by the interaction between diet and ethanol in influencing the phospholipid acyl composition. The alterations in acyl chain distribution indicated that ethanol consumption stimulated elongation of palmitic acid, and depressed the delta 5 desaturation step required for the formation of arachidonic acid. Elongation of palmitic acid was stimulated in studies where animals were fed diets with moderate amounts of fat, whereas depressed synthesis of arachidonate occurred more frequently, but not exclusively, in studies where low-fat diets were employed. These results indicate that there is a significant interaction between diet and ethanol in eliciting changes in hepatic mitochondrial phospholipids. The significant decrease in the linoleic acid content of cardiolipin and the more prominent ethanol-associated alterations in mitochondrial phospholipids suggest that ethanol consumption depresses the phospholipid reacylation activities associated with the mitochondrion. The above observations indicate, therefore, that the alterations occurring in mitochondrial phospholipids are influenced by ethanol-related changes in mitochondrial enzymes involved in phospholipid metabolism. In addition, alterations in the availability of fatty acids due to ethanol-related changes in microsomal elongation and desaturation activities also appear to affect the fatty acid composition of phospholipids in mitochondria from ethanol-fed animals.

Metabolic state of the rat liver with ethanol: comparison of in vivo 31phosphorus nuclear magnetic resonance spectroscopy with freeze clamp assessment

In vivo 31phosphorus nuclear magnetic resonance spectroscopy was used to measure the hepatic metabolic state in various groups of rats given ethanol, a control liquid diet or a solid chow diet. The use of selective presaturation pulses applied to the broad phosphorus resonances of immobile phospholipids permitted reliable determination of ATP/ADP ratios by quantitation of the ATP-beta and ATP-gamma peak areas. ATP/ADP ratios were depressed by both techniques in rats chronically ingesting ethanol compared to pair-fed animals consuming the control liquid diet. These differences were observed regardless of whether ethanol feeding was continued up to the time of investigation or whether it was discontinued for 24 hr prior to study. Acute alcohol administration in chow-fed rats, not previously ingesting ethanol, did not lower hepatic ATP/ADP ratios by either methodology. In all cases, liver ATP/ADP ratios assessed by 31phosphorus nuclear magnetic resonance spectroscopy were higher than those measured by high-performance liquid chromatography. However, parallel decreases in hepatic ATP/ADP ratios were observed with chronic ethanol consumption by both 31phosphorus nuclear magnetic resonance spectroscopy and the biochemical method, confirming the utility of in vivo 31phosphorus nuclear magnetic resonance spectroscopy for assessment of the hepatic bioenergetic status. The difference in absolute ATP/ADP ratios by the two methods may to some degree be explained by binding effects of ADP with proteins or mitochondrial membranes, rendering it partially invisible to nuclear magnetic resonance or alternatively, by breakdown of high energy phosphate bonds with freeze clamp extraction.

Biochemical and morphological alterations of baboon hepatic mitochondria after chronic ethanol consumption

Baboons fed ethanol (50% of total calories) chronically develop ultrastructural alterations of hepatic mitochondria. To determine whether mitochondrial functions are also altered, mitochondria were isolated from nine baboons fed ethanol chronically and their pair-fed controls. At the fatty liver stage, ADP-stimulated respiration was depressed in ethanol-fed baboons by 59.4% with glutamate, 43.2% with acetaldehyde, 45.1% with succinate and 51.1% with ascorbate as substrates. A similar decrease was noted in the ADP/O ratio (14 to 28%) and respiratory control ratio (20 to 44%) with all substrates. Similar alterations of mitochondrial functions were observed in baboons with more advanced stages of liver disease, namely fibrosis. These changes after ethanol treatment were associated with decreases in the enzyme activities of mitochondrial respiratory chain: glutamate, NADH and succinate dehydrogenase (42, 24 and 28%, respectively), glutamate-, NADH- or succinate-cytochrome c reductase (42, 27 and 32%, respectively) and cytochrome oxidase (59.6%). The content of all cytochromes was also decreased in ethanol-fed baboons, especially aa3 (57%). Moreover, [14C]leucine incorporation into mitochondrial membranes was depressed by 21% after ethanol treatment. On the other hand, glutamate dehydrogenase activities of serum and cytosol in ethanol-fed baboons were significantly higher than those in pair-fed controls. Morphologically, mitochondria of ethanol-fed baboons were larger than those of pair-fed controls. However, the mitochondrial protein content per mitochondrial DNA was unchanged. From these results, we conclude that, morphologically and functionally, hepatic mitochondria in baboons are altered by chronic ethanol consumption; it is noteworthy that these changes are fully developed already at the fatty liver stage, and that morphological alteration appears to reflect the damage of mitochondrial membranes rather than an adaptive hypertrophy.

Ethanol-related changes in liver microsomes and mitochondria from the monkey, Macaca fascicularis

Four Macaca fascicularis monkeys were maintained 1 year on a liquid diet containing 26% of calories as ethanol. Four control animals were fed a liquid diet of equivalent calories with protein, carbohydrate, and fat being substituted for ethanol calories. In liver mitochondria prepared from ethanol-fed monkeys (ethanol mitochondria), respiratory control was lowered 20% due to a decrease in state 3 respiration (28%). This was also accompanied by a 20% decrease in ADP translocation into ethanol mitochondria. The major change was a 61% decrease in cytochrome oxidase activity. The respiratory rate in the presence of uncoupler was also lowered 14%, but the decrease was not statistically significant. In contrast with our earlier observations with Macaca nemestrina, no significant ethanol-induced changes were observed in enzyme activities associated with the microsomal electron transport system, and no ethanol-elicited fatty liver was evident. The major changes in fatty acid composition of microsomal and mitochondrial phospholipids were increased amounts of palmitoleic and oleic acids, and decreased amounts of linoleic and arachidonic acids.