Uteroplacental blood flow in the hypertensive, term pregnant, spontaneously hypertensive rat.

Carbohydrate overfeeding throughout pregnancy prevents the progressive fall in blood pressure to normotensive levels during the last week of gestation in the spontaneously hypertensive rat. Cardiac output, organ blood flows, and vascular resistances, measured with radioactive-labeled microspheres, were compared in three groups: carbohydrate-supplemented (hypertensive) term-pregnant rats, control-fed (normotensive) term-pregnant rats, and control-fed (hypertensive) nonpregnant rats. Blood pressure remained elevated in the carbohydrate-supplemented pregnant rats because the normal decrease in total peripheral resistance did not occur. There were no significant differences in organ blood flows between hypertensive and normotensive pregnant rats, with the exception of a 26% lower placental blood flow in the hypertensive versus the normotensive rats. Carbohydrate overfeeding was associated with reduced litter size but did not affect fetal growth. Both placental blood flow and litter size were inversely related to mean arterial blood pressure at term. This may be a useful model of essential hypertension during pregnancy.