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

Metabolic effects of beta-adrenergic receptor blockade in advanced alcoholic cirrhosis

It has been postulated that the adverse metabolic effects of beta-adrenergic blockade with propranolol in cirrhosis may be related to altered delivery and utilisation of oxygen, particularly in patients with advanced alcoholic liver disease (ALD). Consequently, in 10 patients with decompensated ALD, we assessed (a) systemic and hepatic oxygen delivery (DO2), extraction ratio (%O2E) and consumption (VO2), (b) myocardial VO2 (assessed by the rate-pressure product [RPP], together with full systemic and splanchnic haemodynamics) and (c) hepatic redox state (HRS), measured indirectly by the arterial ketone body ratio (KBR i.e. ratio of acetoacetate/beta-hydroxybutyrate), prior to and following intravenous propranolol (0.1-2 mg/kg). Results are expressed as mean +/- S.E.M. Propranolol reduced DO2 (700 +/- 33 vs. 583 +/- 32 ml/min/m2, p < 0.05) and myocardial VO2 (RPP 72 vs. 58, p < 0.05). The %O2E increased however, (18.5 +/- 1.3 vs. 22.6 +/- 1.6%, p < 0.05), resulting in unaltered systemic VO2 (127 +/- 7.3 vs. 131 +/- 6.9 ml/min/m2, p > 0.10). Similarly hepatic VO2 did not change. KBR was not altered (0.44 +/- 0.08 vs. 0.48 +/- 0.07), and in fact improved in two patients (Child C12 and C13) from 0.17 to 0.34 and 0.12 to 0.27, respectively. In conclusion, the results of this study suggest that an underlying O2 debt exists in patients with advanced alcoholic cirrhosis and that beta-adrenergic blockade with propranolol 'normalises' the O2 supply-consumption relationship resulting in more efficient O2 utilisation without adversely affecting HRS. The mechanism of this action may be related to the antagonism of beta 2-mediated arteriovenous shunting resulting in appropriate blood redistribution.

Effects of acute alcohol intoxication on gluconeogenesis and its hormonal responsiveness in isolated, perfused rat liver

Rats were acutely administered ethanol as a primed constant infusion in order to produce sustained blood ethanol levels of 8-12 or 55-65 mM. At the end of ethanol infusion the livers were either freeze-clamped in vivo or isolated and perfused for metabolic studies. The rate of gluconeogenesis and its responsiveness to phenylephrine (10 microM), prostaglandin F2 alpha (5 microM) and glucagon (10 nM), as well as the redox state of the cytosolic NAD(+)-NADH system were assessed in livers isolated from acutely ethanol-treated rats, and subsequently perfused without ethanol. For liver clamped in vivo, high- but not low-ethanol treatment decreased the ATP content by 31% and slightly increased ADP and AMP content, resulting in a decreased energy charge (11%). Glutamate and aspartate content was also increased in high-dose ethanol-infused rats with no changes in malate and 2-oxoglutarate content. Gluconeogenesis with saturating concentrations of lactate (4 mM)+pyruvate (0.4 mM) was delayed in reaching a plateau in the livers of high-dose ethanol-treated rats and its response to all three stimulators was impaired. Low-dose ethanol treatment only decreased the liver response to phenylephrine. While the perfused livers of low-dose ethanol-treated rats displayed no changes in adenine nucleotide content, the livers of high-dose ethanol-treated rats had a decreased ATP (35%) and an increased AMP (77%) content, paralleled by a fall in the total adenine nucleotides (14%) and energy charge (14%). No differences were observed between the saline- and ethanol-treated rats with respect to malate-aspartate shuttle intermediate concentration in perfused livers. Also, the livers of high-, but not low-dose ethanol-treated rats had a more negative value of NAD(+)-NADH redox state as compared to the livers of control rats. The data suggest that acute ethanol intoxication produces changes in liver metabolism and its responsiveness to hormones/agonists that are demonstrable for at least 2 hr after isolation and perfusion of the liver.

Interaction of ethanol with beta-carotene: delayed blood clearance and enhanced hepatotoxicity

Because we had found that ethanol interacts with retinol, we investigated whether it also affects its precursor, beta-carotene. In 14 baboons fed ethanol (50% of total energy) for 2 to 5 yr with a standard amount of beta-carotene (one 200-gm carrot/day), levels of beta-carotene were much higher than in controls fed isocaloric carbohydrate, both in plasma (122.5 +/- 30.9 nmol/dl vs. 6.3 +/- 1.4 nmol/dl; p less than 0.005) and in liver (7.9 +/- 1.1 nmol/gm vs. 1.8 +/- 0.5 nmol/gm; p less than 0.001). Even 20 days after withdrawal of the carrots, plasma beta-carotene levels remained higher in alcohol-fed baboons than in controls (10.1 +/- 3.8 nmol/dl vs. less than 0.1 nmol/dl). Next, the diet was supplemented with beta-carotene beadlets: in four pairs of baboons given a low dose of beta-carotene (3 mg/1,000 kcal), plasma levels were significantly higher in alcohol-fed animals than in controls, even when expressed per cholesterol (although the latter increased with alcohol intake). Seven pairs of animals were given a higher dose (30 mg/1,000 kcal) of beta-carotene for 1 mo, followed, in four pairs, by 45 mg for another month. On cessation of beta-carotene treatment, plasma levels decreased more slowly in the alcohol-fed baboons than in the controls. Percutaneous liver biopsy specimens revealed that liver concentrations of beta-carotene correlated with plasma levels but were higher in the alcohol-fed baboons than in the control baboons, whereas the beta-carotene-induced increase in liver retinoids was lower (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic alcohol intoxication decreases the serum level of hepatitis B surface antigen in transgenic mice

Hepatitis B virus (HBV) infections with an unusual serological profile, viz. positivity of HBV-DNA in the absence of hepatitis B surface antigen (HBsAg), have been described in alcoholics. This atypical pattern could be due to a low circulating level of viral particles rendering HBsAg undetectable with commercial kits, whereas HBV-DNA remains positive using the highly sensitive hybridization technique. We hypothesize that the well-known alcohol-induced impairment of protein secretion could also concern HBsAg particles and leads to a decrease in serum levels of the HBs antigen. To verify this hypothesis, we used HBsAg-positive transgenic mice as an animal model. Twelve HBsAg+ mice were separated into two groups; one group (n = 6) was submitted to increasing alcoholisation over an 18-week period, while the other (n = 6) was water fed. Seven HBsAg- littermates acted as controls: three received the alcohol regimen and the remaining four water. Chronic excessive alcoholisation lead to a significant decrease in serum HBsAg concentrations, while there was no obvious change in liver S mRNA. Ultrastructural studies showed a significant decrease in the number of microtubules in the livers of alcohol-fed mice. Finally, immunohistochemical studies performed at the end of the experiment showed a greater accumulation of HBsAg in the livers of HBsAg+ alcohol-fed (mainly located in the centrilobular area) than in the HBsAg+ water-fed mice. Our results (i) validate our initial hypothesis that chronic alcohol abuse leads to a decrease in serum HBsAg concentrations. This could explain, in part at least, the serological dissociations which were observed. (ii) Confirm the utility of screening serum HBV-DNA in alcoholics.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

Hepatic collagen synthesis in patients with alcoholic and nonalcoholic liver disease

To examine the synthesis of hepatic collagen in patients with alcoholic and nonalcoholic liver disease, liver biopsy specimens were incubated in vitro with 14C-proline, and the radioactivity of the newly synthesized protein-bound 14C-hydroxyproline was measured. Mean hepatic collagen synthesis was 0.82 +/- 0.19 pmole of 14C-hydroxyproline/g liver/2 h in control subjects without histological liver fibrosis. Hepatic collagen synthesis was increased in patients with alcoholic and nonalcoholic liver diseases, especially in those with alcoholic fibrosis, alcoholic cirrhosis and chronic active hepatitis. The raised collagen synthesis in alcoholic liver disease rapidly decreased after withdrawal of alcohol. When alcoholic liver disease were compared with nonalcoholic liver disease, there was no significant difference in hepatic collagen synthesis.

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.

The effect of the prostaglandin analogue-misoprostol on rat liver mitochondria after chronic alcohol feeding

Rats fed ethanol (36% of total calories in a nutritionally adequate liquid diet) for 5 weeks develop functional alterations of hepatic mitochondria and steatosis of the liver. At the fatty liver stage, ADP-stimulated respiration of mitochondria was depressed in ethanol fed rats by 30% (p less than 0.001) with glutamate + malate and by 23% (p less than 0.001) with succinate as substrates. A similar decrease was noted in the respiratory control ratio (RCR) (34% and 29%, respectively). The total lipid content of the liver increased 2.6 fold (p less than 0.001). Mitochondrial dysfunction could be prevented, in part, by the treatment with a synthetic derivative of prostaglandin E1, misoprostol, at a mean daily dose of 80 micrograms/kg of body weight. The RCR with glutamate + malate as substrates was improved by 36% (p less than 0.05). We conclude that misoprostol attenuates several functional alterations in liver mitochondria during alcohol feeding.

Attenuation of alcohol-induced hepatic fibrosis by polyunsaturated lecithin

Characteristic features of alcoholic liver injury include fibrosis and striking membrane alterations, with associated phospholipid changes. To offset some of these abnormalities, a 10-yr study was conducted in baboons: 12 animals (eight females, four males) were fed a liquid diet supplemented with polyunsaturated lecithin (4.1 mg/kcal) for up to 8 yr, with either ethanol (50% of total energy) or isocaloric carbohydrate. They were compared with another group of 18 baboons fed an equivalent amount of the same diet (with or without ethanol), but devoid of lecithin. In the two groups, comparable increases in lipids developed in the ethanol-fed animals, but striking differences in the degree of fibrosis were seen. Whereas at least septal fibrosis (with cirrhosis in two) and transformation of their lipocytes into transitional cells developed in seven of the nine baboons fed the regular diet with ethanol, septal fibrosis did not develop in any animals fed lecithin (p less than 0.005). They did not progress beyond the stage of perivenular fibrosis (sometimes associated with pericellular and perisinusoidal fibrosis) and had a significantly lesser activation of lipocytes to transitional cells. Furthermore, when three of these animals were taken off lecithin, but continued on the same amount of the ethanol-containing diet, they rapidly (within 18 to 21 mo) progressed to cirrhosis, accompanied by an increased transformation of their lipocytes to transitional cells. These results indicate that some component of lecithin exerts a protective action against the fibrogenic effects of ethanol. Because we had previously found that choline, in amounts present in lecithin, has no comparable action, the polyunsaturated phospholipids themselves might be responsible for the protective effect.

Interaction of ethanol with enflurane metabolism and toxicity: role of P450IIE1

Administration of enflurane (EF), a widely-used anesthetic agent, sometimes results in occult liver injury. As hepatic cytochromes P450 oxidize EF to a reactive intermediate, we assessed whether one such microsomal enzyme, ethanol-inducible P450IIE1, plays an obligatory role in EF metabolic activation and hepatotoxicity. Liver microsomes from rats fed ethanol (36% of total calories for 14 days) oxidized 1 mM EF (measured by its defluorination) at rates nearly 10-fold greater than those from control rats, reflecting the markedly enhanced content of immunoreactive microsomal P450IIE1 in the former animals. P450IIE1 involvement in hepatic EF oxidation was further suggested by the pronounced inhibition of microsomal defluorination noted with P450IIE1 antibodies and with ethanol, a specific substrate for this enzyme. EF administration to rats treated chronically with ethanol caused significant elevations in plasma levels of aspartate and alanine aminotransferases and glutamate dehydrogenase, indicative of hepatic injury, whereas concurrent treatment of naive rats with EF and ethanol failed to produce the same effect. Our results imply that ethanol-inducible P450IIE1 is the primary catalyst of hepatic EF bioactivation and that the increased bioactivation occurring in vivo secondary to chronic ethanol consumption is attendant with an increased incidence of EF hepatotoxicity.

S-adenosyl-L-methionine attenuates alcohol-induced liver injury in the baboon

Chronic ethanol consumption by baboons (50% of energy from a liquid diet) for 18 to 36 mo resulted in significant depletion of hepatic S-adenosyl-L-methionine concentration: 74.6 +/- 2.4 nmol/gm vs. 108.9 +/- 8.2 nmol/gm liver in controls (p less than 0.005). The depletion was corrected with S-adenosyl-L-methionine (0.4 mg/kcal) administration (102.1 +/- 15.4 nmol/gm after S-adenosyl-L-methionine-ethanol, with 121.4 +/- 11.9 nmol/gm in controls). Ethanol also induced a depletion of glutathione (2.63 +/- 0.13 mumol/gm after ethanol vs. 4.87 +/- 0.36 mumol/gm in controls) that was attenuated by S-adenosyl-L-methionine (3.89 +/- 0.51 mumol/gm in S-adenosyl-L-methionine-methanol vs. 5.22 +/- 0.53 mumol/gm in S-adenosyl-L-methionine controls). There was a significant correlation between hepatic S-adenosyl-L-methionine and glutathione level (r = 0.497; p less than 0.01). After the baboons received ethanol, we observed the expected increase in circulating levels of the mitochondrial enzyme glutamic dehydrogenase: 95.1 +/- 21.4 IU/L vs. 13.4 +/- 1.8 IU/L; p less than 0.001, whereas in a corresponding group of animals given S-adenosyl-L-methionine with ethanol, the values were only 30.3 +/- 7.1 IU/L (vs. 9.6 +/- 0.7 IU/L in the S-adenosyl-L-methionine controls). This attenuation by S-adenosyl-L-methionine of the ethanol-induced increase in plasma glutamic dehydrogenase (p less than 0.005) was associated with a decrease in the number of giant mitochondria (assessed in percutaneous liver biopsy specimens), with a corresponding change in the activity of succinate dehydrogenase, a mitochondrial marker enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Taking the tension out of the portal system. An approach to the management of portal hypertension in the 1990s

The past decade saw the emergence of sclerotherapy and vasoactive pharmacologic agents as alternatives to surgery in the prevention and treatment of variceal haemorrhage. Despite encouraging results from clinical trials with regard to the prevention of rebleeding, these modalities of therapy have made no major impact on survival. This failure to alter radically the clinical outcome results from the fact that in many patients with cirrhosis death is primarily related to the degree of hepatic decompensation rather than the prevention or control of variceal bleeding. Advances in our knowledge of vasoactive mediators, receptor function, and altered vascular reactivity have provided increased insight into the circulatory disturbances that characterise cirrhosis and portal hypertension. Earlier and more aggressive pharmacologic intervention with single or combination drug therapy may inhibit fibrogenesis, reduce portal vascular resistance, and improve liver function and therefore provide effective prophylaxis against variceal haemorrhage. The emergence of reliable prognostic indices for variceal bleeding should help identify patients at risk who would benefit from prophylaxis with either drugs or sclerotherapy. Transplantation will be increasingly considered in the patient at high risk of recurrent bleeding before the stage of severe hepatic decompensation (the risks of the transplant then become very much greater), as the definitive means for reducing mortality in cirrhosis and portal hypertension.

In vivo hepatic energy metabolism during the progression of alcoholic liver disease: a noninvasive 31P nuclear magnetic resonance study in rats

We investigated serially in vivo the ratios of phosphorylated metabolites and the intracellular pH in the livers of rats fed ethanol chronically to evaluate the relation between changes in energy metabolism and the progression of alcoholic liver disease with 31P nuclear magnetic resonance spectroscopy. 31P nuclear magnetic resonance spectra of the liver were acquired noninvasively from rats pair-fed a nutritionally adequate liquid diet containing ethanol or an isocaloric amount of dextrose with an implanted intragastric cannula for up to 24 wk. A high blood alcohol level was constantly maintained. The spectra were obtained using a surface coil combined with a ferrite screen to eliminate nuclear magnetic resonance signals derived from the superficial muscles. Contaminating 31P nuclear magnetic resonance signals arising from abdominal tissues other than the liver were eliminated from the spectra by digital subtraction. Throughout the study the inorganic phosphate/beta-ATP peak area ratio observed in alcohol-fed rats was found to be consistently elevated in comparison with the control rats (at 3 to 5 wk alcohol-fed rats = 1.20 +/- 0.10, control rats = 0.78 +/- 0.04, p less than 0.05.; at 22 to 24 wk alcohol-fed rats = 1.23 +/- 0.10, control rats = 0.81 +/- 0.06, p less than 0.05.; mean +/- S.E.). The phosphomonoesters/beta-ATP ratio tended to be higher in alcohol-fed rats when compared with control rats. The intracellular pH measured by the chemical shift of the inorganic phosphate peak showed no significant differences between alcohol-fed rats and control rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Impaired oxygen utilization. A new mechanism for the hepatotoxicity of ethanol in sub-human primates

The role of oxygenation in the pathogenesis of alcoholic liver injury was investigated in six baboons fed alcohol chronically and in six pair-fed controls. All animals fed alcohol developed fatty liver with, in addition, fibrosis in three. No evidence for hypoxia was found, both in the basal state and after ethanol at moderate (30 mM) or high (55 mM) levels, as shown by unchanged or even increased hepatic venous partial pressure of O2 and O2 saturation of hemoglobin in the tissue. In controls, ethanol administration resulted in enhanced O2 consumption (offset by a commitant increase in splanchnic blood flow), whereas in alcohol fed animals, there was no increase. At the moderate ethanol dose, the flow-independent O2 extraction, measured by reflectance spectroscopy on the liver surface, tended to increase in control animals only, whereas a significant decrease was observed after the high ethanol dose in the alcohol-treated baboons. This was associated with a marked shift in the mitochondrial redox level in the alcohol-fed (but not in control) baboons, with striking rises in splanchnic output of glutamic dehydrogenase and acetaldehyde, reflecting mitochondrial injury. Increased acetaldehyde, in turn, may aggravate the mitochondrial damage and exacerbate defective O2 utilization. Thus impaired O2 consumption rather than lack of O2 supply characterizes liver injury produced by high ethanol levels in baboons fed alcohol chronically.

Sensitivity of liver mitochondrial functions to various levels of ethanol intake in the rat

Mitochondrial function appears to be an early target for ethanol toxicity, however it is not clear to what extent the effects of ethanol, which occur at levels of intake lower than those already reported in the literature, can induce an alteration of it. To produce different levels of ethanol intake, the spontaneous consumption of ethanol by genetically low (UChA) and genetically high (UChB) rats, as well as the forced intake obtained by offering 10% v/v ethanol solution as the only source of drinking fluid, were employed. The O2 uptake by liver mitochondria of rats submitted to these conditions in the presence of glutamate + malate, succinate or ascorbate + TMPD, was measured polarographically with a Clark electrode at 25 degrees C. Results indicate that alterations of the hepatic mitochondrial function can be detected at levels of ethanol intake much lower than those previously reported. Whereas, a level of a daily ethanol intake of 2-3 g/kg body weight in UChA rats under free choice was insufficient to produce detectable changes in the mitochondrial function, the latter was decreased in the high ethanol consumers (UChB), which drank 4-5 g/kg per day under free choice conditions, and in both strains forced to drink 10% ethanol as only source of fluid, which produced intakes of about 7 g/kg per day. Therefore, mitochondrial dysfunction may contribute to effects observed even at low levels of ethanol intake.

Calcium status and calcium-regulating hormones in alcoholics

To elucidate effects of chronic ethanol consumption on clinical chemical parameters reflecting overall calcium homeostasis 34 hospitalized male alcoholics and 35 age-matched controls were studied during the winter season. Serum concentrations of 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 were reduced by 28% (p less than 0.01) and 24% (p less than 0.02) among the alcoholics as compared to the controls, respectively. Dietary intake of vitamin D3 did not differ significantly between the groups. The calcium level was below lower limit of reference in nine alcoholics (26%). Serum concentrations of parathyroid hormone and phosphorus were within normal ranges in both groups, and no differences were observed in levels of magnesium, vitamin D-binding protein, calcitonin, or alkaline phosphatase. In conclusion, it is possible that the activities of enzymes crucial in vitamin D3 metabolism may be altered in alcoholics.

Hepatic adenine nucleotide metabolism measured in vivo in rats fed ethanol and a high fat-low protein diet

Rats fed a diet high in fat and low in protein continuously infused by intragastric cannula were given ethanol for 2 to 6 months in order to examine the response of liver adenine nucleotides to changes in systemic PO2. Hepatic adenine nucleotides were measured in vivo monthly using liver obtained by biopsy from rats while a high blood alcohol level was maintained. Ethanol decreased hepatic ATP and the total adenylate pool, but did not change the levels of ADP and AMP. Adenylate energy charge showed only a tendency to be decreased. Carotid arterial PO2 was mildly but significantly lower in ethanol-fed rats compared to the pair-fed controls. Pure O2 inhalation for 3 min increased the PO2 four times in the ethanol and control-fed rats, and tended to increase ATP and decrease ADP in ethanol-fed rats as well as pair-fed controls. It restored the energy charge to a normal level in the ethanol-fed rats. Ten per cent O2 + 90% N2 inhalation for 3 min decreased the PO2 to 40 mm Hg in both the ethanol-fed and control rats, and this rapidly decreased ATP. This effect was significantly greater in the ethanol-fed rats compared to the controls. The total adenylate pool and the energy charge were decreased only in ethanol-fed rats. The results show that the reduced energy stores in the rat liver induced by ethanol are rapidly responsive to changes in PO2. Thus, the livers of ethanol-fed rats were more vulnerable to transient hypoxia than were controls.

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.

International Commission for Protection against Environmental Mutagens and Carcinogens. ICPEMC Working Paper No. 15/2. Metabolism and metabolic effects of ethanol, including interaction with drugs, carcinogens and nutrition

Different pathways of alcohol metabolism, the alcohol dehydrogenase pathway, the microsomal ethanol-oxidizing system and the catalase pathway are discussed. Alcohol consumption leads to accelerated ethanol metabolism by different mechanisms including an increased microsomal function. Microsomal induction leads to interactions of ethanol with drugs, hepatotoxic agents, steroids, vitamins and to an increased activation of mutagens/carcinogens. A number of ethanol-related complications may be explained by the production of its first metabolite, acetaldehyde, such as alterations of mitochondria, increased lipid peroxidation and microtubular alterations with its adverse effects on various cellular activities, including disturbances of cell division. Nutritional factors in alcoholics such as malnutrition are discussed especially with respect to its possible relation to cancer.

Increased prolyl hydroxylase activity and collagen synthesis in hepatocyte cultures exposed to superoxide

Primary monolayer cultures of rat hepatocytes at confluence were exposed to an exogenously added source of superoxide, and its influence on collagen synthesis was examined. Superoxide was generated by the addition of dihydroxyfumarate to the culture medium. Exposure of hepatocytes to dihydroxyfumarate greatly stimulated the activity of prolyl hydroxylase and the synthesis of collagen. A significant increase in prolyl hydroxylase activity was observed with 5 micrograms per ml dihydroxyfumarate in 24 hr relative to that in the untreated cultures. Maximum stimulation of greater than 3-fold compared to the control value was elicited by 25 micrograms per ml dihydroxyfumarate. When scavengers of superoxide such as superoxide dismutase and Cu(Lys)2 were added in the medium, the increase in prolyl hydroxylase activity induced by dihydroxyfumarate was nearly abolished. Experiments with actinomycin D indicated that synthesis of new RNA was involved in the stimulation of prolyl hydroxylase activity. Analysis of collagen synthesis in cultures exposed to dihydroxyfumarate also showed a marked increase compared to that of the untreated cultures. The presence of superoxide dismutase in the medium significantly reduced the increase in collagen synthesis. Our results indicate that superoxide mediates the stimulation of collagen synthesis in hepatocytes. These findings may provide a possible explanation for excess collagen formation during induced liver fibrosis.

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.

Ethanol-induced hepatic fibrosis in the rat: role of the amount of dietary fat

We have made a comparison between groups of rats fed ethanol and a diet that received intragastric infusion of ethanol continuously for prolonged periods varying only in the amount of fat in the diet (percentage of total calories as fat was 5, 25, and 35%). A fourth group of rats fed high fat (32% of calories) and a diet marginal in protein, vitamins and minerals was also studied. Control rats were pair-fed dextrose in isocaloric amounts. For rats fed diets containing 5, 25, 32, and 35% fat, the average blood alcohol levels achieved were 216, 224, 266 and 353 mg/100 ml, respectively. Average weight gains of the ethanol fed rats were: 15.4, 19.6, 14.7, and 14.9 g/week, respectively. Serum alanine aminotransferase (ALT) levels of the ethanol-fed rats averaged 123, 292, 144, and 213 units/liter, respectively. ALT levels in pair-fed controls for the rats fed 32% fat averaged 62 and those of chow-fed controls averaged 49 units/liter. Comparison of liver biopsy-semiquantified morphological findings revealed an increased 3-4+ fatty change in the ethanol-fed rats also fed the high fat rats. Moreover, fibrosis was only observed centrilobularly in rats fed diets with varying fat content (5, 25, 32, or 35% of calories): 0/16, 10/17, 4/6, and 3/7 rats, respectively, over a 5-mon period of feeding. Electron microscopy showed that ito cells predominated in the scarred areas. The mechanism for the centrilobular necrosis-fibrosis was investigated in rats given a diet of ethanol plus 32% fat diet by measuring the level of adenine nucleotide in repeated liver biopsies in five pair of rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic hemodynamics and oxygen consumption in alcoholic fatty liver assessed by organ-reflectance spectrophotometry and the hydrogen clearance method

Hepatic blood flow and estimated hepatic oxygen consumption were studied in rats treated chronically with ethanol by organ-reflectance spectrophotometry and the hydrogen clearance method. In the withdrawal state from ethanol, the concentration of hemoglobin in the hepatic tissue (delta Er569-650), the estimated hepatic oxygen consumption (estimated VO2) and the regional liver blood flow decreased significantly in rats treated chronically with ethanol in comparison with their controls. On the other hand, there was no significant difference in the estimated oxygen saturation of the hepatic blood hemoglobin (estimated SO2) between both groups. That is, an increase in oxygen extraction, which was exhibited by a decrease in the estimated SO2, did not occur in rats treated chronically with ethanol in spite of a decrease in blood supply. Thus, in the withdrawal state from ethanol, both oxygen delivery to the liver and oxygen utilization in the liver were disturbed at the stage of alcoholic fatty liver.

Choline fails to prevent liver fibrosis in ethanol-fed baboons but causes toxicity

To determine how choline supplementation affects the liver and whether it can protect against ethanol-induced liver injury, baboons were fed either normal or choline-supplemented diets, each with or without ethanol. Eighteen baboons were pair-fed for 3 to 4 years liquid diets with 50% of total energy as ethanol or isocaloric carbohydrate; ten animals were given our regular diets, whereas in eight the choline content was increased 5-fold. Six additional animals were fed individually with the control diets (with or without additional choline). With both ethanol-containing diets, ethanol intake was comparable and resulted in hepatic steatosis and striking mitochondrial lesions, with increases in serum bilirubin and SGOT, SGPT and glutamate dehydrogenase activities. In addition, of the five animals fed alcohol with the regular diet, one progressed to incomplete cirrhosis and two others developed perivenular and associated perisinusoidal fibrosis. Similarly, in the four baboons fed alcohol with choline supplementation, incomplete cirrhosis developed in one and perivenular fibrosis in two. Collagen deposition was demonstrated by immunoperoxidase with a specific antibody against procollagen Type III. These animals also displayed proliferation of myofibroblasts in the perivenular area and transformation of fat-storing cells to transitional cells in the perisinusoidal space, with associated enhanced collagen fiber deposition. Thus, in baboons, choline supplementation failed to prevent alcohol-induced steatosis and fibrosis. All parameters remained normal in the eight baboons fed the regular control diet. However, in the choline-supplemented controls, serum bilirubin, SGOT and glutamate dehydrogenase activities increased moderately and serum albumin decreased. Occasional fat droplets appeared in hepatocytes with mitochondrial changes (enlargement and alterations of the cristae) and an abundance of "myelin" figures in the cytoplasm, indicating that choline supplementation exerts moderate hepatotoxicity.

Ethanol and lipids

The interaction of ethanol with lipid metabolism is complex. When ethanol is present, it becomes a preferred fuel for the liver and displaces fat as a source of energy. This favors fat accumulation. In addition, the altered redox state secondary to the oxidation of ethanol promotes lipogenesis, for instance, through enhanced formation of acylglycerols. The depressed oxidative capacity of the mitochondria injured by chronic alcohol feeding also contributes to the development of the fatty liver. Accumulation of fat acts as a stimulus for the secretion of lipoproteins and the development of hyperlipemia. Hyperlipemia may also be facilitated by the proliferation of the endoplasmic reticulum after chronic ethanol consumption and the associated increase of enzymes involved in the production of triglycerides and lipoproteins. The propensity to enhance lipoprotein secretion is offset, at least in part, by a decrease in microtubules and an impairment of the secretory capacity of the liver. The level of blood lipids depends on the balance between these two opposite changes: At the early stage of alcohol abuse, when liver damage is still small, hyperlipemia will prevail, whereas the opposite occurs with severe liver injury. When hyperlipemia occurs, it involves all lipoprotein classes, including high density lipoprotein (HDL). The latter have been suggested to be responsible for the lower incidence of coronary complications of moderate drinkers compared to teetotalers, but in fact, the subtype of HDL involved (HDL3) differs from the HDL2 subtype associated with protection.

Alcohol-nutrition interaction: 1984 update

Alcohol remains a prevailing cause of malnutrition resulting in a variety of deficiency states secondary to decreased intake of nutrients. In addition to various well described primary malnutrition syndromes, secondary malnutrition may result from the interaction of ethanol with nutrient digestion, absorption or utilization. Some of the latter alcohol-nutrient interactions have been recently defined and their pathogenesis is discussed in this review. Included are interactions with thiamine, folic acid, vitamin A and disorders secondary to amino acid imbalances. The rationale for various forms of therapy is reviewed, including the treatment aimed at correcting the "hypermetabolic state" in alcoholics ad the pitfalls of excess nutrient administration (particularly as it pertains to pyridoxine, vitamin A and amino acids). The desirability of recognizing early precirrhotic stages of alcoholic fibrosis is emphasized, in order to start therapy prior to the medical and/or social disintegration of the alcoholic.