Systemic compliance, renal hemodynamics, and sodium excretion in hypertension

Extracellular fluid volume (ECF), plasma volume (PV), glomerular filtration rate (GFR), renal plasma flow (RPF), efferent arteriolar oncotic pressure (pi E), sodium output (UNaV), and sodium clearance (CNa) were determined in 150 men including 50 normal controls (NC) and 100 sustained essential hypertensive patients (EH). Total effective vascular compliance (TEVC) and central venous pressure (CVP) were measured in 17 normotensives and 24 EH. EH had a decreased RPF and TEVC (P less than 0.001), while CVP and pi E were higher than in NC (P less than 0.001). ECF, GFR, UNaV, and CNa were identical in EH and NC. A positive correlation between RPF and CNa (P less than 0.01) and a negative correlation between pi E and CNa existed in both groups with a significant reset of the curve in EH: For any given RPF or pi E the CNa was higher in EH. In the overall population TEVC was negatively correlated with CVP (P less than 0.01) and pi E (P less than 0.01); CVP was positively correlated with pi E (P less than 0.01). The results suggest that physical properties of the low pressure system could participate in the natriuretic adaptation of the kidney in EH man.