The effect of papillectomy on renal function in the rat during hydropenia and after an acute saline load.

Abstract

The effect of unilateral papillectomy on renal function in the rat was compared with the effect of partial nephrectomy which produced a similar decrease in glomerular filtration rate (G.F.R.) in the presence of an intact papilla. Under hydropenic conditions the kidney with papillectomy had a higher urine flow rate, sodium excretion rate, fractional sodium excretion, and osmolar clearance, while urine osmolality was lower. After an acute saline load the differences in sodium and water excretion disappeared, and fractional excretion of sodium and water were significantly higher in both types of kidney damage than in the contralateral control kidney. Free water reabsorption was lower in the papillectomized kidney after saline loading. Thus removal of the papilla resulted in abnormalities in the renal handling of salt and water which varied with the state of hydration of the animal and which were distinct from the effects of a reduction in G.F.R. by partial nephrectomy. It was concluded that the site of nephron loss, whether mainly in the renal medulla or in the cortex, may be another factor, in addition to G.F.R. and tubular reabsorption, which influences sodium and water excretion by the moderately damaged kidney.