Abstract
A number of the mesoionic compounds known as a new class of heterocycles have been examined in the search for potential therapeutic agents and their biological activities have been reviewed recently by Kier and Roche (1), and Ackermann (2). Oehme et al. (3) studied some mesoionic 3- or 3, 4-substituted sydnonimines and found that in urethane anesthetized rats the sydnonimines were hypotensive only in high doses (0.02 mM/kg i.v.), the effect not being pronounced, and reported that in the rat duodenum and the guinea pig ileum 3, 4-diphenylsyndnonimine had a spasmolytic effect equipotent to papaverine. However, no detailed cardiovascular actions of sydnonimines have so far been reported. Recently we found that the newly synthesized 3-substituted sydnonimines (4) have potential pharmacological actions such as vasodilating, vasoconstricting, hypotensive, hypertensive, sympathomimetic, or spasmolytic actions. This paper reports the chemical structureactivity relationship and mechanisms of the cardiovascular actions of 3-substituted sydnonimines, especially those of 3-morpholinosydnonimine hydrochloride (CV-664, SIN-1), a potent hypotensive and spasmolytic compound.
