Induction of tyrosine aminotransferase in rat liver by epinephrine and theophylline

Abstract

The effects of epinephrine on alcohol dehydrogenase activity and on rates of ethanol elimination were determined in rat hepatocyte culture. Continuous exposure of the hepatocytes to epinephrine (10 μM) in combination with dexamethasone (0.1 μM) enhanced alcohol dehydrogenase activity on days 4–7 of culture, whereas neither hormone alone had an effect. The increased alcohol dehydrogenase activity was associated with an increased rate of ethanol elimination. Acute addition of 10 μM epinephrine to hepatocytes maintained in culture with 0.1 μM dexamethasone did not change alcohol dehydrogenase activity, but resulted in an immediate marked, but transitory, increase in ethanol elimination within the first 5 min after the addition of the hormone. Prazosin, an α1-adrenergic blocker, and antimycin, an inhibitor of mitochondrial respiration, were powerful inhibitors of the transient increase in ethanol elimination, whereas 4-methylpyrazole was only partially inhibitory. These observations indicate that epinephrine has a chronic effect in increasing alcohol dehydrogenase activity and ethanol elimination and, also, an acute transient effect of increasing ethanol elimination which is not limited by alcohol dehydrogenase activity.