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
Kock NG, Tibblin S, Schenk WG. Mesenteric Blood Flow Response to Glucagon Administration: During Temporary Exclusion of the Liver. Arch Surg. 1970;100(3):280–283. doi:10.1001/archsurg.1970.01340210056014
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