The effect of acute maternal hemorrhage on the release of catecholamines in the pregnant ewe and the fetus.

Five chronically instrumented pregnant ewes and their fetuses were studied to assess the effect of acute maternal hemorrhage. The hemorrhage was produced in two stages; during the first stage 15% of the total maternal blood volume was removed, and then in a second stage an additional 15% was removed. Biophysical and biochemical variables were monitored. Plasma dopamine, norepinephrine, and epinephrine were determined by a sensitive radioenzymatic assay. A significant rise in maternal and fetal catecholamines was observed following an estimated maternal blood volume depletion of 30%. During a 15-minute recovery period, the maternal catecholamine concentrations returned to normal, while the fetal concentrations remained elevated. These changes were accompanied by significant changes in maternal and fetal homeostasis. The significance of these findings is discussed.