Influence of magnesium sulphate and isradipine on human placental cotyledon fetal vessels in vitro.

Increased systemic vascular resistance and blood pressure during pregnancy may be due to impaired prostacycline PGI(2)-thromboxan (TX) A(2) balance. The aim of the study was to compare the influence of magnesium sulphate and isradipine on the placental vascular resistance induced by stable thromboxan A(2) analogue U 46619 in experimental bilateral perfusion of the human placental cotyledon. The research used the experimental model described by Schneider et al. [Am. J. Obstet. Gynecol. 114 (1972) 822]. The control group consisted of six placental lobule perfusions lasting 120 min each. Constant increase in perfusion pressure of mean value 185% of the initial pressure was obtained from about the 60th min of the experiment and maintained till the end. Having obtained constant increase in perfusion pressure from the 60th min of the experiment, magnesium sulphate and isradipine were administered along with thromboxan A(2) analogue U 46619 into the fetal circulation. Both drugs lowered perfusion pressure, experimentally increased by thromboxan A(2) analogue U 46619. The onset of magnesium sulphate activity was quicker than isradipine. According to the results of our in vitro study, magnesium sulphate and isradipine may have a beneficial effect on vascular resistance of cotyledon vessels in PIH in vivo, too.