A NONSYMPATHOMIMETIC EFFECT OF CYCLOPENTAMINE AND -MERCAPTOETHYLAMINE IN THE RABBIT ILEUM

¹ Department of Pharmacology, West Virginia University Medical Center, Morgantown, West Virginia

Pretreatment of rabbits with reserpine did not alter the dose-response relationships of cyclopentamine and -mercaptoethylamine (MEA) in inhibiting the spontaneous activity of the isolated ileum. Previous work relating the structure of sympathomimetic amines to the effect of reserpine on sensitivity to the amines suggested that these two compounds might not be functioning as sympathomimetics in the ileum. This possibility was consistent with the fact that reserpine did not alter the dose-response curve of papaverine and was supported by the inability of adrenergic blockade to antagonize the effects of cyclopentamine and MEA in the ileum. Studies of the ability of cyclopentamnine, MEA, papaverine, atropine and tripelennamine to antagonize the stimulatory action of acetylcholine, histamine and barium on the ileum indicated that cyclopentamine and MEA were acting as nonspecific spasmolytics, similar to papaverine. Attention is called to the fact that this nonspecific spasmolytic action of cyclopentamine and MEA is only one facet of their complex pharmacodynamics.