The pharmacological actions of murexine (urocanylcholine).

Murexine or urocanylcholine is a naturally occurring choline ester of urocanic acid which was found in very large amounts in the hypobranchial body of Murex trunculus and other prosobranchiate molluscs. In vertebrates and invertebrates, it was found to possess marked neuromuscular blocking and nicotinic actions, but was almost devoid of muscarinic effects. The blocking action of murexine was considered, on the basis of experimental and clinical evidence, to be of the "depolarizing" type. It was weaker than, but qualitatively very similar to, that produced by suxamethonium. The nicotinic action of murexine was stronger than that of suxamethonium in both experimental animals and human beings.