BACKGROUND: To investigate the effect of nitroglycerin in vitro and in vivo on human uterine contractile activity. METHODS: In vitro myometrial strips were obtained from six pregnant women at term who underwent elective cesarean section. The biopsies were mounted in tissue baths. After spontaneous or oxytocin-induced activity had been accomplished, nitroglycerin in various concentrations was added to the baths and the effects were continuously registered. In vivo, in an open study nitroglycerin was administered as a bolus injection of 100-200 micrograms intravenously to 32 women at cesarean section when uterine relaxation was urgently needed; to 22 other women after vaginal delivery for facilitation of manual removal of retained placentas, and to one patient at vaginal delivery of premature twins. RESULTS: In vitro nitroglycerin induced a dose-dependent inhibition of spontaneous as well as oxytocin-induced myometrial contractile activity. Complete muscular relaxation was obtained at a concentration of 25-50 micrograms/ml. In vivo all patients had rapid effective uterine relaxation after intravenous injection of 100-200 micrograms nitroglycerin. CONCLUSION: Nitroglycerin administered intravenously seems to be a rapid and effective uterine muscle relaxant agent without overt adverse effects on mother or fetus.
BACKGROUND: To investigate the effect of nitroglycerin in vitro and in vivo on human uterine contractile activity. METHODS: In vitro myometrial strips were obtained from six pregnant women at term who underwent elective cesarean section. The biopsies were mounted in tissue baths. After spontaneous or oxytocin-induced activity had been accomplished, nitroglycerin in various concentrations was added to the baths and the effects were continuously registered. In vivo, in an open study nitroglycerin was administered as a bolus injection of 100-200 micrograms intravenously to 32 women at cesarean section when uterine relaxation was urgently needed; to 22 other women after vaginal delivery for facilitation of manual removal of retained placentas, and to one patient at vaginal delivery of premature twins. RESULTS: In vitro nitroglycerin induced a dose-dependent inhibition of spontaneous as well as oxytocin-induced myometrial contractile activity. Complete muscular relaxation was obtained at a concentration of 25-50 micrograms/ml. In vivo all patients had rapid effective uterine relaxation after intravenous injection of 100-200 micrograms nitroglycerin. CONCLUSION:Nitroglycerin administered intravenously seems to be a rapid and effective uterine muscle relaxant agent without overt adverse effects on mother or fetus.