Effect of terbutaline on the human fetal placental circulation.

The effect of terbutaline, a beta2-adrenoceptor stimulator, on the vascular resistance of isolated human placenta was examined. Terbutaline produced no change in basal placental vascular resistance, but when the placental vessels were constricted with angiotensin, terbutaline produced a graded decrease in vascular resistance. The vasodilating effect of a high dose of terbutaline was smaller than the effect 20 microgram of isoprenaline and the effect was significantly blocked by propranolol, a beta-adrenoceptor antagonist. The results suggest that the vasodilating effect of terbutaline on the fetal placental circulation can play a role in the improvement of fetal condition during treatment of premature labour and intrapartum fetal distress.