The Inhibition of Adrenaline by Spasmolytic Agents

Abstract

Summary Isolated segments of duodenum from the duck react to the addition of adrenaline by a biphasic response, contracting and relaxing. Atropine, trasentin 6H, homatropine and neoantergan (2786 R.P.) abolish this contractile response. Hyoscine and hyoscyamine have no effect in concentrations of 105. Rabbit gut is inhibited by adrenaline and l-nor-adrenaline. This action is abolished after neoantergan has been in contact with some segments of gut. Rabbit uterus contracts with adrenaline or neoantergan. In the presence of the latter the former inhibits movement of the uterus. The pressor response to adrenaline and l-nor-adrenaline in spinal cats is inhibited by atropine, trasentin and neoantergan in high doses (atropine sulphate 20ṁ0 mg./kg.). Certain differences between l-adrenaline and l-nor-adrenaline are discussed. A tentative hypothesis is offered to account for the adrenolytic activity found in a wide variety of compounds. This is an extension of MacGregor’s well-known explanation for the reactions of cocaine and adrenaline, based on certain common structural features in the adrenolytic agents discussed.