Renal clearance of human and rat albumins in the rat.

Abstract

Experiments were done to investigate whether molecular discrimination occurred in the renal handling of two species of serum albumin. Human albumin, 40 mg, was infused into rats; it was removed from serum (t1/2 equal to 15.8 hr) more rapidly than previously reported measurements of removal of endogenous rat albumin (t1/2 equal to 46 hr). Human albumin was cleared by the rat kidney at a constant rate of 0.0026 mul/min--a value virtually identical to that of rat albumin (0.0020 mul/min). In rats with proteinuria following the single iv injection of puromycin aminonucleoside, human albumin was removed from serum with a half-life of 17.6 hr. During the development of the nephrotic syndrome, the renal clearances of human and rat albumin increased proportionately. Despite the difference in the serum concentration and rates of removal of the two species of albumin, renal handling of the two species was similar. Thus the kidney did not appear to discriminate in its handling of these two proteins.