Role of sodium balance on maintenance of blood pressure in the chronic phase of two-kidney, one-clip hypertension

Abstract

Blood pressure and sodium balance have been studied after unclipping, nephrectomy and sham operation of ischemic kidney in the chronic phase (16 weeks) of two-kidney, one clip hypertension.In hypertensive rats the fractional excretion of sodium was 85.5 +/- 2.3% and blood pressure (BP) was significantly increased (187.1 +/- 4.5 mmHg, p less than 0.001).Removal of either the constricting clip or ischemic kidney induced a decrease of BP to normal level whereas sham operation did not produce any change.However, rats submitted to these three experimental manipulations showed, at 1, 2, 3 and 4 days, and at 3 weeks, similar changes in sodium excretion.In the groups with unclipping or nephrectomy of ischemic kidney, water intake was less and urine volume smaller than in the sham operated group.These results suggest that a positive sodium balance is not important to maintain hypertension at this stage and that changes in sodium balance, after both unclipping and nephrectomy of ischemic kidney, have no influence in BP normalization.