Changes in central hemodynamics during pregnancy in renal hypertensive rats.

Central hemodynamics during late pregnancy were studied in normotensive rats and in rats with short-standing and "established" renal hypertension. In normal pregnancy cardiac output was increased 33%, due to increased stroke volume while mean arterial pressure and systemic resistance were reduced 17 and 40% respectively. The same changes, though less pronounced were noted during pregnancy in rats with short-standing renal hypertension, where cardiac output was increased 31%, due to equal increases in heart rate and stroke volume while systemic resistance was reduced only 27%. By contrast, no significant cardiac output increase, nor any resistance reduction was noted during pregnancy in rats with established hypertension. Thus, renal hypertension in rats seems to interfere with circulation during pregnancy mainly by restricting both the cardiac output increase and the systemic resistance reduction seen during normal pregnancy. This restriction seems to be more pronounced the longer the duration of hypertension.