Effects of glucagon, histamine, and perhexiline on the ischemic canine mesenteric circulation

This study was designed to evaluate the effectiveness of three pharmacologically dissimilar vasodilating agents (histamine, perhexiline, and glucagon) in reversing the hemodynamic and metabolic changes after digoxin-induced vasoconstriction of the canine mesenteric circulation. Total blood flow to the gut was measured with a flowmeter, and the microsphere technique was applied to measure intraintestinal blood flow distribution and to calculate fractional blood flows to the muscular and the mucosal-submucosal compartments of the gut. In the conscious and in the anesthetized animals before surgery, over 90% of total mesenteric blood flow was distributed to the mucosal-submucosal compartment. Surgical manipulation caused a redistribution of blood flow such that only 78% was distributed to the mucosal-submucosal compartment. Intravenous administration of digoxin decreased total blood flow to the intestine by 26%, oxygen consumption 9% and increased mesenteric vascular resistance by 42%. All three vasodilatory agents infused intraarterially restored total blood flow and oxygen consumption to predigoxin values. Glucagon, the most potent vasodilator, and perhexiline increased blood flow to all layers within the intestinal wall, while histamine caused selective vasodilation in the muscle compartment of the gut.