INFLUENCE OF PARTIAL-HEPATECTOMY IN RATS ON THE ACTIVITY OF HEPATIC-MICROSOMAL ENZYMATIC SYSTEMS

The influence of partial hepatectomy on the activity of the hepatic mi crosomal enzymatic systems was determined in rats. Cytochrome P-450, c ytochrome b(5), four mixed functional oxidase (MFO) activities (micros omal aniline hydroxylase, p-nitroanisole O-demethylase, aminopyrine N- demethylase and NADPH cytochrome c reductase) and glutathione levels w ere measured in unhepatectomized rats (control group) and in hepatecto mized rats 12 h, 24 h, 3 days and 6 days after 70% hepatectomy. Follow ing surgery the remaining lobes of the liver grow rapidly in order to restore the original liver mass. Partial hepatectomy significantly red uces cytochrome P-450 and bs content in the remaining liver as well as the four MFO activities studied. But when the enzymatic systems are e xpressed as nmoles/mg microsomal protein, only cytochrome P-450 shows statistical differences. The hepatic biotransformation capacity of dru gs and xenobiotics decreases during the regeneration period due to the reduction of hepatic mass rather than because of a reduction of their metabolic capacity. Glutathione levels are increased after partial he patectomy but increased glutathione-dependent protector mechanisms are not expected.