Role of ethanol metabolism in the ethanol-induced increase in splanchnic circulation

In this study we report the effect on splanchnic hemodynamics of acute oral ethanol at doses ranging from 0.25 to 4.0 g/kg body wt. Flows were determined by use of a radioactive microsphere technique. Ethanol was found to increase portal blood flow by 23-57%. In awake rats this increase reached a plateau at the 0.5 g/kg dose. In ketamine-anesthetized rats, the increase was observed only at doses of 3.0 g/kg or more, with the response at doses of 0.5, 1.0, and 2.0 g/kg being suppressed by ketamine. Inhibition of alcohol dehydrogenase by intra-arterial administration of 4-methylpyrazole resulted in suppression of the liver blood flow increase after ethanol was administered to awake animals. Ethanol in the range of doses studied did not result in changes in blood glucagon levels. Rats fed ethanol-containing diets for 4 wk and withdrawn for 18 h had the same response to acute oral ethanol as did naive rats. It is suggested that ethanol metabolism mediates the effects of ethanol on splanchnic blood flow. An increase in splanchnic blood flow when concurrent with an increase in liver O2 consumption induced by ethanol might protect the liver from hypoxic damage.