Some Aspects of the Relationship Between Plasma and Urine Erythropoietin.

Abstract

Simultaneous comparative assays were carried out on plasma and urinary erythropoietin (EPF) from rabbits with varying degrees of induced anemia and periods of hypoxia. Bled anemic rabbit plasma showed distinct EPF elevations at 15 and 10% hematocrit levels with minimal elevation in urine only at 15% hema-tocrit level. Phenylhydrazine anemic rabbit plasma showed marked elevation of EPF at all hematocrit levels from 25 to 10% with lesser amounts present in the corresponding urines. Time of appearance and potency of EPF in both plasma and urine of hypoxic rabbits were strikingly similar with highest levels at 24 and 48 hours and a return to normal values at 120 hours. At no time were EPF levels higher in urine than in plasma. The results suggest similar rather than separate identity of plasma and urinary EPF and are compatible with the concept that urinary EPF represents partial excretion of plasma content.