RATE-INCREASING ACTION OF CORTICOTROPIN AND OF α-INTERMEDIN IN THE ISOLATED MAMMALIAN HEART

Abstract

A preparation of corticotropin and o-intermedin were found to exhibit an unusual heart rate-increasing action in the heart-lung preparation of the dog. The effect was unpredictable from one experiment to the next but was often very striking. The chronotropic action was not linked to effects upon impulse propagation and force of contraction as in the case of the sympathomimetic amines. [alpha]-Intermedin was shown to have the same effect in normal heart-lung preparations and in those almost completely free of intrinsic sympathomimetic amines, obtained from dogs heavily treated with reserpine.