Glutathione metabolism and glucose 6-phosphate dehydrogenase activity in experimental liver injury.

Increased activities of liver glucose-6-phosphate dehydrogenase (G6PD, EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6PGD, EC 1.1.1.44) in the pentose phosphate cycle were accompanied with a depletion of reduced glutathione (GSH) following an intragastric administration of carbon tetrachloride (CCl4) to rats. Oxidized glutathione (GSSG) also decreased remarkably, keeping the GSSG: GSH ratio constant. No significant alteration of glutathione reductase (EC 1.6.4.2.), glutathione peroxidase (EC 1.11.1.9) and malic enzyme (EC 1.1.1.40) activities in the supernatant and gamma-glutamyl transpeptidase (gamma-GTP, EC 2.3.2.2) activity in the homogenate of the injured liver were observed. Furthermore, no marked difference in the GSH-synthesizing activity was found between control and CCl4-intoxicated liver. An intraperitoneal injection of GSH produced a significant increase in liver GSH content in control rats but not in CCl4-treated rats; G6PD activity was not affected. Intraperitoneal injections of diethylmaleate resulted in continuously diminished levels of liver GSH without any alteration of liver G6PD activity. In vitro disappearance of GSH added to the liver homogenate from CCl4-treated rats occurred enzymatically and could not be prevented by the addition of a NADPH-generating system. The results suggest that increased G6PD activity in CCl4-injured liver does not play an important role in the maintenance of glutathione in the reduced form and that the decreased GSH content in the injured liver might be caused by enhanced GSH catabolism not due to gamma-GTP.</p

Injurious effects of ethanol on rat Kupffer cells.

The effects of ethanol on rat Kupffer cells were studied functionally and morphologically. Eight g ethanol per kg body weight per day was intragastrically administered to rats for 7 days. An isocaloric glucose solution was administered to control rats. The phagocytic activity of the reticuloendothelial system was measured by the carbon clearance method (57 mg carbon particles per kg body weight) on the 7th day. Kupffer cells having phagocytized carbon particles were counted under the light microscope. Kupffer cells were also observed by scanning electron microscopy. Both the carbon clearance and Kupffer cell number were lower in ethanol-administered rats (32 +/- 8 X 10(-4) mg/ml; 0.6 +/- 0.3/0.01 mm2 liver lobule) as compared to control rats (63 +/- 15; 3.1 +/- 1.0). Microvilli and filopodia of Kupffer cells were fewer in ethanol-administered rats than in control rats. Carbon clearance correlated with Kupffer cell number per 0.01 mm2 liver lobule and liver weight. These results suggest that the decrease in carbon clearance induced by ethanol is due mainly to the decrease in Kupffer cell number and partly to the decrease in Kupffer cell activity as demonstrated by the disappearance of microvilli and filopodia.</p

An approach to nutritional therapy of hepatic encephalopathy by normalization of deranged amino acid patterns in serum

A mixture with essential and nonessential amino acids high in branched chain amino acids and low in aromatic amino acids (Fischer solution), and another synthetic mixture of branched chain amino acids containing 3 amino acids associated with the urea cycle (Hep-OU) were infused to control subjects and patients with severe hepatic disease. Alterations in serum aminograms, blood ammonia levels and electroencephalograms following the infusion were studied and compared with those obtained by a commercially available amino acid mixture. Short-term or continuous infusion of a commercially available amino acid solution to cirrhotic patients caused an increase in methionine, phenylalanine and tyrosine and a decrease in branched chain amino acids. These post-infusion results were similar to the patterns seen in hepatic encephalopathy. In cirrhotic patients, infusion of Fischer solution which contains small quantities of methionine and phenylalanine produced an increase in the concentrations of these 2 amino acids, probably because of impaired utilization by the injured liver. No marked alterations in serum aminograms, however, were observed in cirrhotic patients either immediately after, or 3 h after, the end of the Hep-OU infusion. Reduction of methionine, tyrosine and phenylalanine levels and elevation of the molar ratio of (valine+leucine+isoleucine) / (phenylalanine+tyrosine) were significant. The infusion of Hep-OU to patients with liver cirrhosis or subacute hepatitis resulted in clinical and neurological improvements and the restoration of the molar ratio of branched chain amino acids/aromatic amino acids.</p

Metabolism of branched-chain amino acids in rats with acute hepatic failure: a tracer study using 15N-leucine.

Fulminant hepatic failure (FHF) was produced in rats with intraperitoneal injection of D-galactosamine. Control rats received only physiological saline. 15N-leucine (200 mg/kg of body weight) was injected into the rats via the tail vein. Arterial blood was drawn before and 5, 15, 30 and 60 min after the injection of 15N-leucine. 15N-amino acids were determined quantitatively by gas chromatography and mass spectrometry. The plasma 15N-leucine level decreased logarithmically in the same manner in both groups. This result suggests that leucine is mainly metabolized in extrahepatic tissues. The incorporation of 15N into plasma isoleucine and valine was not significantly different between the groups. Plasma alanine and glutamine concentrations increased in controls and decreased in FHF rates after the injection. The incorporation of 15N into plasma alanine in rats with FHF was significantly later than in controls. This result may suggest that undergoing hyperammonemia causes to form more glutamine from glutamate in extrahepatic sites as the same manner as for chronic hepatic failure. Additionally, insulin levels increased temporarily after the injection of leucine in both groups. This increase may play a role in the decrease in plasma isoleucine and valine concentrations after injection of leucine.</p

Demonstration of enzymatic activity converting azathioprine to 6-mercaptopurine

The enzymatic conversion of azathioprine to 6-mercaptopurine was detected at pH 6.5 with rat liver supernatants, although the non-enzymatic reaction predominated at pH 7.0 and 7.5. Glutathione S-transferase may catalize this conversion. Activities of the enzyme in liver with both zathioprine and 1,2-dichloro-4-nitrobenzene as substrate decreased upon carbon tetrachloride-induced hepatic injury. These results may explain an ineffectiveness of azathioprine in patients with severe hepatic damage.</p

A vegetable protein-rich diet for the treatment of liver cirrhosis

Twelve patients were administered a vegetable protein-rich diet, which was low in methionine and high in the branched-chain amino acid (BCAA) to aromatic amino acid (AAA) molar ratio, and an animal protein-rich diet, high in methionine and low in the BCAA/AAA molar ratio. These diets were administered successively for one week each. Actually ingested amounts of tyrosine and methionine were significantly lower during the feeding of the vegetable protein-rich diet than the animal protein-rich diet. Serum methionine concentrations increased while on the animal protein-rich diet and decreased following the switch to the vegetable protein-rich diet. No other amino acid concentrations were affected. Significant differences were not observed in nitrogen balance or serum protein concentrations.</p

Liver Injury Following Long-Term Administration of Large Doses of Sake to Rats

The hepatotoxic effect on rats of long-term (55 weeks) administration of sake (a rice wine, 17% ethanol by volume) at large doses (average 12.6 g ethanol/kg body weight/day) was investigated in order to gain an insight into the reasons for the high incidence of liver fibrosis in Japanese alcoholics. Rats grew favorably under the experimental conditions, and daily variations in blood ethanol and acetaldehyde levels ranged from 3.8 to 21.1 mM and from O to 3.5 μM, respectively. Fatty and fibrotic liver was shown histologically and biochemically in sake-administered rats

Evaluation of Talbot's Safety Zone of Infusion Volume and Osmolality in Infusion Therapy for Decompensated Liver Cirrhosis

Problems with infusion therapy for correcting fluid and sodium imbalance in decompensated liver cirrhosis (DLC) were investigated by establishing the safety zone of Talbot et al. for parenteral fluid therapy in 4 DLC patients infused with over 900 ml of fluid each day for at least 9 days. The safety zone was different in each case. The safe infusion volume decreased and the safe electrolyte concentration shifted to a lower osmolality when there was ascites with renal failure than ascites without renal failure. Infusion therapy was performed without deterioration of the water and sodium balance in those patients whose infusion volume and fluid osmolality were in the safety zone. In contrast, ascites retention increased and peripheral edema appeared in patients whose infusion volume and osmolality were out of the safety zone. Therefore, the safety zone should be determined repeatedly during infusion therapy.</p

Bile Acid and Ammonia-Induced Brain Edema in Rats

Infusion of bile acid such as chenodeoxycholic acid or deoxycholic acid through the carotid artery of rats produced reversible and unilateral opening of the blood-brain barrier without any tissue damage. Intravenous drip infusion of ammonium acetate during the opening resulted in severe edema of the brain. The results suggest the importance of bile acid and ammonia for the pathogenesis of brain edema frequently observed in acute hepatic failure

Elevation of Ammonia Contents in the Cerebral Hemisphere under the Blood-Brain Barrier Opening

Elevation of ammonia contents was observed 1 hr following infusion of 4% ammonium acetate only in the cerebral hemisphere where reversible opening of the blood-brain barrier was induced by intracarotid injection of 0.1% deoxycholic acid. This finding suggests that ammonia may contribute to hepatic encephalopathy, when the permeability of the blood-brain barrier is altered