EFFECT OF TOXEMIA THERAPY ON UTERINE DYNAMICS

Effect on uterine dynamics of magnesium sulfate, hydralazine hydrochloride, and cryptenamine acetates was evaluated by in vitro and in vivo techniques. Magnesium sulfate depressed myometrial activity in vitro. Hydralazine hydrochloride decreased the rate and increased the amplitude of contraction of human myometrial strips. In concentrations of 6 to 8 mEq. per liter of maternal serum, magnesium reduced the uterine activity of 7 pre-eclamptic patients in active spontaneous labor. The effect of each agent on myometrial and hemodynamic variables was measured in 3 pregnant rhesus monkeys during both normotensive and induced hypertensive states. Serum magnesium concentrations of 6 to 8 mEq. per liter resulted in a reduction of arterial blood pressure, a greater decrease in extrinsic myometrial resistance, and an increase in uterine artery blood flow. Intravenous administration of hydralazine hydrochloride in quantities sufficient to produce a statistically significant decrease in arterial blood pressure did not significantly alter uterine artery blood flow or average intra-amniotic pressure. Responses to cryptenamine acetates were inconclusive. © 1969.