Exogenous and Endogenous Histamine-Induced Potassium Release as Modified by the Antihistaminics

¹ From the Department of Pharmacology, The University of Vermont, Burlington, Vermont

Exogenous histamine or endogenous release of histamine, mediated through the action of compound 48/80 in doses of 50 µg/kg in the cat, results in a similar elevation of the concentration of potassium in the extracellular fluid. That these actions are due to the release of histamine and not to 48/80 per se has been determined by an analysis of the time-potassium release curves in both cases and the effectiveness of the antihistaminics in altering the depressor responses and potassium changes in each case. Diphenhydramine, pyrilamine and phenergan were used as representative antihistaminics. Phenergan, the most specific agent of this group, was shown to be most effective in depressing the exogenous and endogenous histamine induced hyperpotassemia. It is concluded that the alterations produced by exogenous histamine on potassium distribution in the cat are similar to those changes produced by endogenous histamine.