Different types of sympathomimetic α-receptors

Abstract

Sympathomimetic effects have been studied on the isolated vas deferens of the rat, in the isolated jejunum of the rabbit and on the cardiovascular system of the cat. (–)-Noradrenaline (1-R configuration), (+)-noradrenaline (1-S configuration) and dopamine as well as a number of homologues were used as agonists. The adrenergic blocking drugs piperoxan, phentolamine, yohimbine, aceperone and the tranquillising drugs chlorpromazine, (–)-mepromazine, haloperidol, droperidol and spiramide as well as bulbocapnine were used as antagonists. The results obtained with both agonists and antagonists provide evidence that the structural requirements for drugs to react with and to activate α-receptors in the vas deferens and the rabbit intestine are different; epinine and dopamine have an identical mechanism of action.