Effects of nephrectomy on renal salt and water transport in the remaining kidney

Abstract

Fluid, sodium, and potassium transport was studied in proximal and distal tubules in rats in which one kidney had been removed 2 wk after a suprarenal aortic clamp had been placed to prevent adaptive changes in glomerular filtration rate (GFR) in the experimental kidney. Free flow micropuncture techniques were used and tubular fluid (TF) samples analyzed for inulin, sodium and potassium. In addition, peritubular total protein concentrations and luminal and peritubular hydrostatic pressures were measured. The following changes were observed 15 hr after unilateral nephrectomy: a significant increase in single hephron GFR; unchanged absolute proximal tubular reabsorption rates of fluid and sodium; increased delivery of fluid into distal tubules; increased distal tubular reabsorption of sodium, but of insufficient magnitude to prevent natriuresis; and an augmentation of distal tubular potassium secretion. Reduction of single nephron GFR to control levels by aortic clamping abolished the natriuresis following nephrectomy.