Renal function in experimental chronic hydronephrosis. IV. Renal handling of sodium and water.

The reabsorption and excretion of sodium, chloride, potassium and water were investigated subsequent to loading with saline solution before and after unilateral hydronephrosis with partial obstruction to flow had been induced in 23 dogs by ligation of the ureter over an indwelling catheter. In the experimental kidney the increase in the total excretion of sodium and chloride and of water in per cent of GFR and the decrease in the reabsorption of sodium, chloride and potassium in per cent of the filtered loads were statistically significant. The glomerulotubular balance was altered statistically probably significantly, but the relation between the capacities for reabsorption of sodium and glucose was maintained. The renal pelvic dilatation was measured and plotted against the degree of renal functional impairment. A statistically significant inverse correlation was noted between renal pelvic volume and reabsorption of sodium and of chloride in per cent of the filtered loads. The osmolality of the urine was the parameter showing the most marked difference between the hydronephrotic and the contralateral kidney. For sodium and chloride the difference between the two sides in the reabsorbed amount in per cent of the filtered load was correlated probably significantly to the degree of renal pelvic dilatation.