Spasmolytic activity of cinnamedrine and papaverine in isolated rat uterine muscle.

The objective of this work was to thoroughly examine the smooth muscle relaxing properties of cinnamedrine, compared with papaverine, in vitro, using rat uterus. Cinnamedrine and papaverine both exhibited dose-related spasmolytic activity in the isolated spontaneously contracting rat uterus and in uterine tissue pretreated with oxytocin to augment spasms. The IC50's for cinnamedrine and papaverine were 36.2 and 7.7 microM respectively; the IC50's after oxytocin pretreatment were 25.7 microM for cinnamedrine and 10.0 microM for papaverine. Neither hormonal status of the rats, with respect to their estrus cycle, nor oxytocin pretreatment of the isolated tissues noticeably affected the activity of either cinnamedrine or papaverine.