Mesenteric Blood Flow Response to Glucagon Administration

Abstract

In recent years cardiovascular effects of glucagon have been demonstrated both in animals and man. Following a single injection of glucagon the hepatic blood flow increased approximately 100%.^1,2 This increase in hepatic blood flow is mainly due to a vasodilatory action of glucagon on the splanchnic vascular bed.³ Glucagon exerts positive inotropic and chronotropic effects on the heart.^4,5 In dogs, a single injection of glucagon increased the cardiac output 36% and the coronary artery flow 54%.⁶ The greatest flow increase produced by glucagon (190%) was recorded in the superior mesenteric artery.⁷ The mechanism by which glucagon exerts its cardiovascular effects is not known. Originally, Shoemaker et al¹ suggested that the increase in hepatic blood flow could be a consequence of increased metabolic activity of the liver incident to rapid glycogenolysis. However, the action of glucagon on cardiac performance was as effective on the isolated