THE ANTIACCELERATOR CARDIAC ACTION OF QUININE AND QUINIDINE

¹ Department of Pharmacology, Harvard Medical School, Boston, Mass.

Quinine and quinidine antagonize the cardioaccelerator action of epinephrine in the heart-lung preparation of the dog. The action is similar to that of the veratrum alkaloids, veratramine and jervine, in that it sets in abruptly, is persistent, and is not prevented or abolished by atropine. The potency of quinine is only 1/500 of that of veratramine and 1/10 of that of jervine when studied under identical conditions. The antiaccelerator cardiac action of quinine and quinidine is less selective than that of veratramine and jervine; doses lower than would be required to cause complete inhibition of the positive chronotropic effect of epinephrine cause severe irregularities of rate and rhythm and a marked negative inotropic effect.