Modification by glucagon of the splanchnic vascular responses to activation of the sympathicoadrenal system

Abstract

The vasodilatory effect of glucagon on the splanchnic vascular bed was studied in anesthetized dogs during experimentally induced and simulated activation of the sympathicoadrenal system. Blood flow in the superior mesenteric artery was recorded using the electromagnetic technique. When the splanchnic blood flow had been reduced to about 50 per cent by bleeding, intravenous injection of glucagon restored the blood flow to approximately control level. When an activation of the sympathetic outflow to the splanchnic vascular bed was simulated by electrical splanchnic nerve stimulation, the vasoconstrictory response to the stimulation was abolished or modified by glucagon injection. Finally, the vasodilatory effect of glucagon in the mesenteric vascular bed could also be demonstrated when vasoconstriction due to catecholamine infusion was present. Glucagon did not, however, influence the vasoconstrictory response to catecholamines in other peripheral vascular beds. The mechanism for the vasodilatory action of glucagon is briefly discussed.