Hepatic glutathione levels in D-penicillamine-fed ethanol-dependent rats.

Ethanol oxidation is accomplished primarily by alcohol dehydrogenase. However, a microsomal system involving hydrogen peroxide formation operates at elevated ethanol concentrations. Removal of the resultant hydrogen peroxide may depend on the activity of glutathione peroxidase. In the study, we have examined the effect of chronic ethanol exposure on hepatic glutatione levels and found that ethanol exposure resulted in elevations of hepatic reduced and oxidized glutathione. The dietary inclusion of the sulfhydryl amino acid, D-penicillamine, increased hepatic reduced glutathione (GSH) in both ethanol-dependent and control rats. However, D-penicillamine did not have a differential effect on hepatic GSH when comparing ethanol-dependent and control animals. Following two weeks exposure, the exclusion of ethanol and/or D-penicillamine from the diet for 24 hours resulted in a significant decrease in hepatic GSH.

Stimulation of adenylate cyclase from isolated hepatocytes and Kupffer cells.

Hepatocytes and Kupffer cells were separated from rat liver after prelabeling the Kupffer cells with colloidal iron and perfusion of the liver with digestive enzymes. The activity of several enzymes from Kupffer cells and hepatocytes was compared to validate this method of cell separation. The ratios of hepatocyte to Kupffer cell specific activities of glucose-6-phosphatase, 5'-nucleotidase, adenylate cyclase, and acid phosphatase were 20, 0.39, 0.18, and 0.078, respectively. Adenylate cyclases from hepatocytes and Kupffer cells were stimulated by fluoride ion, GTP, and catecholamines. Hepatocyte adenylate cyclase was also stimulated by glucagon, secretin, vasoactive intestinal polypeptide, and by prostaglandin E1, whereas, the Kupffer cell enzyme was completely insensitive to these hormones. The stimulation of hepatocyte adenylate cyclase by combinations of glucagon plus secretin, or glucagon plus vasoactive intestinal polypeptide, were equivalent to the sum of the individual stimulations. This suggests that the hepatocyte has specific receptors for glucagon and for vasoactive intestinal polypeptide and secretin. Prostaglandin E1 stimulation of hepatocyte adenylate cyclase was not additive to the stimulation caused by polypeptide hormones or catecholamines, nor did prostaglandin E1 decrease stimulation caused by these hormones. Although prostaglandin-sensitive adenylate cyclase was recovered with hepatocytes, 40 to 50% of the total liver prostaglandin-sensitive activity was recovered in a fraction of cell debris mixed with small cells which did not phagocytize colloidal iron.