Abstract

Crystalline glucagon preparations produced a positive chronotropic and inotropic effect on isolated hearts of the dog, cat, guinea pig and rat. No such effects could be demonstrated in isolated rabbit hearts or atria or on hearts of the intact anesthetized dog.

These effects of glucagon are not prevented by pretreating the dog with reserpine but can be abolished or reduced by the adrenergic blocking agent dichloroisoproterenol. Glucagon produced a relaxation and inhibited of spontaneous activity in the isolated rabbit and cat intestine which was similar to that produced by epinephrine and some amorphous insulin preparations.

The above observations make it likely that glucagon has, besides its epinephrine-like effects on the liver, epinephrine-like effects in the isolated heart and intestine of some species. The quantitative data presented indicate that the biological effects observed here are due to the same substance, presumably glucagon, and are most probably not caused by an impurity which contaminates crystalline glucagon.