Regional differences of effects of ethanol on canine blood vessels

In vitro effects of ethanol (0.1-2.0%,v/v) on canine vasculer smooth muscle were studied. Ethanol dose-dependently produced inhibition in both the amplitude and frequency of the spontaneous rhythmic activity of the canine hepatic portal vein, and at concentration of 1.0 +/- 0.2% completely abolished the spontaneous activity. Ethanol evoked dose-dependent constriction, rather than dilatation, in all vascular smooth muscles tested, including femoral, renal, common carotid, and pulmonary arteries, and external jugular, splenic, pulmonary, femoral, renal, and hepatic portal veins. The vasoconstriction effect of ethanol was much stronger on arteries than on the corresponding veins. Based on the contractile tension developed by ethanol, the femoral artery or the external jugular vein appeared to be most sensitive to ethanol among the arteries or veins preparations tested. The present results suggested that ethanol, depending on concentration, may either enhance or decrease excitability of vascular smooth muscles. There were also regional differences of effects of ethanol on canine blood vessels.