PRIMARY EFFECT OF GLUCAGON ON POSITIVE CHRONOTROPISM

Chronotropic and inotropic effects of glucagon were compared with those of norepinephrine using the excised SA node and the papillary muscle preparations cross-circulated with a donor dog. Glucagon was administered i.v. to the donor dog at doses of 1 to 30 μg/kg, which caused a marked chronotropic but less marked inotropic effect. Cardiohemodynamic response to glucagon of anesthetized dogs was simulated by an acceleration induced by atrial pacing. It was concluded that glucagon is more effective on chronotropism than on inotropism, and that its cardiohemodynamic effects are mainly ascribed to the increased heart rate.