Effects of electrical stimulation of the hepatic nerves on acute liver damage were examined using isolated rat liver perfused in situ, 24 hours after intraperitoneal injection with D-galactosamine (800 mg/kg). The leakage of lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) from the liver was used as markers of acute liver damage. In perfused livers after treatment with galactosamine, nerve stimulation (20 V, 20 Hz, 2 ms) increased the leakage of LDH and AST about 3-fold over the basal level accompanied by the decrease in flow rate, whereas with control livers the leakage of LDH and AST into the effluent was almost undetectable throughout the perfusion. The rapid increase in the leakage of LDH and AST was observed during nerve stimulation even under conditions where perfusion flow was maintained constant. Such effects of hepatic nerve stimulation on galactosamine-treated livers were mimicked well by infusion of noradrenaline or phenylephrine, and inhibited by the alpha1-antagonist bunazosin. Artificial reduction of perfusion flow alone did not induce the rapid leakage of LDH and AST into the effluent. On the other hand, low concentration (10 nmol/L) of noradrenaline only minimally decreased the flow rate but apparently augmented liver cell damage. The acute liver damage augmented by noradrenaline was dependent on extracellular Ca2+. These results indicate that in the liver, already having been injured slightly, the activation of hepatic sympathetic nerves and circulating catecholamines exaggerates acute liver damage through an action on liver cells, which depends on the influx of extracellular Ca2+.