Ovarian steroids and modulation of morphine-induced analgesia and catalepsy in female rats

The effects of dantrolene sodium on the spontaneous and oxytocin-induced contraction of guinea-pig uterus were studied in vitro. Dantrolene reversibly increased the spontaneous contraction frequency of guinea-pig uterus. The effect was not dose-related and was not antagonized by atropine, methysergide or indomethacin. Dantrolene dose dependently and reversibly reduced the contractile responses of guinea-pig uterus to oxytocin. The varying effects of dantrolene on the uterus probably involve inhibition of calcium movement at more than one site of the muscle.