Blood Pressure and Renal Function

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Abstract
The relationship between blood pressure (BP) and renal function was studied in 49 yr old men. Of 3205 men, 2376 took part in a BP screening. By systematic sampling, based on diastolic BP levels varying from very low to very high, 120 subjects were selected. Only subjects who were not on antihypertensive treatment were included. Renal blood flow (RBF), renovascular resistance (RVR), glomerular filtration rate (GFR), filtration fraction (FF) and renal concentrationg capacity were studied in 111 subjects; none had advanced hypertension. With increasing BP there was a decrease in RBF (r = -0.34) and an increase in RVR (r = 0.81) and FF (r = 0.35). The changes in renal haemodynamics occurred gradually from low to high BP and did not start at any particular BP level. With increasing BP GFR was unchanged. An autoregulation of GFR was found at all BP levels studied. Renal concentrating capacity was unchanged. Renal hemodynamics in essential hypertension are adjusted mainly to ensure a constant GFR.