Separated Renal Functions in Patients with Renal Arterial Disease, Pyelonephritis, and Essential Hypertension

Abstract

Function tests of the individual kidneys have been performed during mannitol diuresis and vasopressin infusion in hypertensive patients with essential hypertension, pyelonephritis, and occlusive lesions of one or both main renal arteries or their primary branches. In patients with essential hypertension, glomerular filtration rate and renal plasma flow on the two sides, though depressed, were practically equal, as were urine flow, water, solute, and sodium excretions. Pyelonephritis and branch arterial lesions alike depressed urine flow, glomerular filtration rate, and renal plasma flow in the affected or more-affected kidneys; water, total solute, and sodium excretions were in proportion to glomerular filtration rate. These findings indicate a decrease in numbers of functioning nephrons without a qualitative change in function of those remaining. Occlusive lesion of one main renal artery decreased glomerular filtration rate and renal plasma flow on the affected side; urine flow was relatively more depressed than filtration rate, urinary osmolality was higher, and urinary sodium concentration was sharply decreased, as was the excreted fraction of the filtered sodium load. Bilateral occlusive main arterial lesions sometimes had effects similar to those of unilateral lesions in the sense of greater functional deficits on the more-affected sides. However their functional patterns were not consistent. The enhanced renal sodium reabsorption observed in patients with unilateral and bilateral main renal artery diseases could not be explained solely by decreases in filtered sodium load; this suggests that decreases in intrarenal arterial pressure also affect sodium excretion. Changes in renal functions caused by arterial disease depend on the site of the lesion and not on the pressor mechanism it may evoke.