Experimental hypertension in pregnant sheep. III. Central hemodynamic alterations in the one-kidney model

Experimental renal hypertension, with use of the one-kidney, one-clip model, was produced in nine pregnant ewes who were then studied during the last one third of gestation. The animals were chronically instrumented for the recording of arterial pressure, heart rate, and cardiac output; blood volume was determined weekly. The studies were carried out in four phases; a control period of 2 weeks, a surgery period of 1 week, a constriction or hypertensive period, and a postpartum period of 2 weeks. We detected no significant changes in heart rate or cardiac output during any phase of the study. The arterial pressure significantly increased during the constriction and postpartum phases (p less than 0.05). Blood volume remained relatively stable during the three pregnancy phases but significantly decreased in the postpartum phase (p less than 0.05). Systemic vascular resistance followed a pattern similar to that of the arterial pressure.