Renal rsponse of chickens to infusion of hyperosmotic sodium chloride solution

Abstract

The renal response of chickens to a continuous infusion of 6% NaCl was studied. Glomerular filtration rate (GFR) decreased following infusion of 20 mEq NaCl/kg and continued to fall with continued NaCl infusion while the plasma osmolality and Na concentration rose. Urine flow increased initially and did not fall below control levels until about 40 mEq NaCl/kg had been given, Urine osmolality increased, but the urine did not become hyperosmotic. Tubular maxima for secretion of para-aminohippurate (TmPAH) and reabsorption of glucose (TmG) decreased with GFR, suggesting that changes in GFR result from changes in the number of functioning nephrons. Infusion of PAH through the renal portal system did not change the relationship between TmPAH and GFR. TmPAH decreased more than TmG with small decreases in GFR. Possible explanations for this difference are discussed. In the absence of ability to excrete excess salt, chickens respond to a salt load with a decrease in the number of functioning nephrons, conserving water and tending to reduce plasma osmolality at the expense of excreting waste.