Renal Function in Rats with Unilateral Proteinuria Produced by Renal Perfusion with Aminonucleoside

Abstract

Summary: Left (L) renal perfusion with an aminonucleoside of puromycin (PA), was used to produce unilateral proteinuria in 15 rats to examine the mechanisms responsible for renal salt retention in the nephrotic syndrome. Thirteen control rats underwent L renal perfusion with isotonic saline. Animals were studied 8 (group I) or 13 (group II) days after perfusion. Renal perfusion with saline per se did not change the glomerular filtration rate, renal plasma flow, or absolute and fractional excretion of sodium (Na) from the perfused kidney. PA animals showed a significant decrease in glomerular filtration rate from the perfused kidney and a proportional decrease in the absolute excretion of Na from the PA perfused kidney as compared to the right kidney. The fractional excretion of Na was equivalent in the L and R kidneys of the PA animals. The mean absolute Na excretion from the nonproteinuric R kidney of PA rats was almost twice that of the R kidney of the controls. The increased Na excretion by the nonproteinuric kidney of the PA animals compensated for the sodium retention by the proteinuric kidney.

Speculation: In rats with unilateral proteinuria, unilateral sodium retention occurs due to mechanisms intrinsic to the proteinuric kidney. Systemic natriuretic factors may compensate for the unilateral sodium retention when contralateral kidney is nonproteinuric. When both kidneys are proteinuric, systemic counterbalancing events may not be operative and net sodium retention may result.