[The effect of intravenous cimetidine and histamine on splanchnic circulation in the dogs].

We investigated the effect of cimetidine and histamine on splanchnic circulation in the dogs. Hepatic artery, superior mesenteric artery and portal vein were cannulated to measure each blood pressure. Each blood flow was evaluated utilizing electromagnetic blood flowmetry. And vascular resistances were calculated by measured blood pressure and blood flow. Cimetidine, histamine, 2-PEA (H1-agonist), dimaprit (H2-agonist) and mepyramine maleate (H1-antagonist) were given by intravenous bolus to the dogs. Histamine caused vasodilation of hepatic artery but vasoconstriction of superior mesenteric artery and these effects were similar to the effect of 2-PEA. These hemodynamic responses to histamine were inhibited by H1-antagonist but not inhibited by H2-antagonist. Cimetidine produced dilatation of hepatic artery but constriction of portal vein, superior mesenteric artery and reduced total hepatic blood flow. These effects were not inhibited by H1-antagonist. We concluded that cimetidine did not stimulated H1, H2-receptors rather than had the own effects and that H1-receptor was superior to H2-receptor on splanchnic circulation in the dogs.