EFFECT OF PARASYMPATHETIC AND BETA-ADRENERGIC-BLOCKADE ON THE UMBILICAL CIRCULATION IN THE UNANESTHETIZED FETAL SHEEP

Parasympathetic and β-adrenergic blocking agents were administered to near term chronically instrumented sheep. Parasympathetic blockade resulted in a significant increase in fetal heart rate and fetal arterial blood pressure, with a minimal non-significant increase in umbilical blood flow. β-Adrenergic blockade resulted in a decrease in fetal heart rate and umbilical blood flow, though neither was statistically significant. There was no change in arterial blood pressure. The net result of parasympathetic and β-adrenergic blockade on fetal heart rate suggests that the intrinsic rate is the same as when these influences are present. © 1979 S. Karger AG, Basel.