Effects of vasodilators on mesenteric ischemia and hypoxia induced by hemorrhage

We compared the effectiveness of three pharmacologically and chemically dissimilar vasodilators (histamine, glucagon, and perhexiline) in reversing the hemodynamic and metabolic deficits of intestinal ischemia produced by hemorrhage. With intraarterial infusion into the superior mesenteric artery of anesthetized control dogs, all three agents increased mesenteric blood flow and oxygen consumption without altering systemic arterial blood pressure. Similarly, in the ischemic gut following moderate hemorrhage all three vasodilators increased mesenteric flow and oxygen consumption while reducing vascular resistance and not affecting systemic arterial blood pressure. On a molar basis glucagon was the most potent dilator drug. In severely hemorrhaged dogs whose intestinal blood flow had been reduced nearly 80%, glucagon restored oxygen uptake and vascular resistance to control levels. These findings demonstrate the efficacy of three different vasodilators in reversing the mesenteric ischemia and hypoxia produced by hemorrhage.