Experimental renal hypertension in pregnant sheep. II. Response to a one-kidney model.

Pelvic blood flow was serially determined in 19 pregnant ewes before and after the induction of one-kidney renal hypertension. The six twin gestations and 13 singleton gestations behaved similarly for all parameters, except renal blood flow. After the renal preparatory surgical procedure, there was a 19% increase in mean arterial pressure and an 18% increase in pelvic blood flow, with pelvic vascular resistance being unchanged. After right renal artery constriction, there was a 14% further increase in mean arterial pressure, whereas pelvic blood flow increased only 3.5% and pelvic vascular resistance increased nearly 9%. Thereafter, although the arterial pressure remained elevated, the pelvic blood flow decreased and pelvic vascular resistance increased. Statistical analysis by means of a general linear model and covariance before and after renal artery constriction revealed significant changes in arterial pressures, pelvic blood flow, and pelvic vascular resistance.