Serotonin receptor in rabbit artery

Abstract

The isolated rabbit aortic strip was made to contract by serotonin, norepinephrine, and histamine. Antagonists were applied to differentiate between the receptors of the tissue. Antiserotonins synthesized by Woolley and co-workers selectively inhibited contractions induced by serotonin. The serotinin analogs, BAS [l-benzyl-2-methyl-5-methoxytryptamine]-phenol and BAS, antagonized serotinin only partially, because at high concentration they become contracting agents. However, DBMC (N-dimethylamine-N-benzyl-m-metoxycinnamamide) antagonized fully the 60% submaximal test dose, and it did not show contracting ability at all. Antagonism with these agents was reversible, and it could be overcome by large doses of serotonin. Dibenzyline and DC1 [dichloro-isoproterenol] antagonized serotonin-, norepinephrine-, and histamine-induced contractions almost equally efficiently, and therefore, they are not suited for differentiation between receptors. An antihistaminic, mepyramine antagonized, highly selectively, contractions induced by histamine. Consequently, by use of appropriate concentrations of DBMC, mepyramine, and of their combination, the three receptors can be differentiated. Morphine and LSD [lysergic acid diethylamide], reported to antagonize the effect of serotonin on the other organs, were ineffective.