Effect of glucagon on digital circulation.

The effect of glucagon on the digital circulation was studied in 7 subjects using the digital rheoplethysmograph (RPG). Rheoplethysmograms were continuously recorded while glucagon (0.1 to 2.0 mg) was injected into the brachial artery of the same extremity being studied with the RPG. The injection of glucagon was associated with a "tingling" or "burning" sensation in 3 subjects. The initial response, which was maximal 8 to 27 sec after the injection of glucagon, was constriction of the arteries, veins, and A-V shunts. The late response consisted of reopening of the arteries and veins. However, in some patients, there was RPG evidence of persistent constriction of the A-V shunts. It is suggested that the late response is similar to that observed in reactive hyperemia and following injection of bradykinin and, therefore, may be related to local release of vasoactive substances by glucagon.