Plasma Disappearance of 125 I-Labeled Erythropoietin in Anesthetized Rabbits 1

Summary

The rate of plasma disappearance of ¹²⁵I-labeled highly purified human urinary erythropoietin (ESF) was compared with that of unlabeled partially purified human urinary ESF in anesthetized rabbits. Plasma T1/2 values for both the labeled and unlabeled ESF were essentially biphasic. The mean half-time disappearance of ¹²⁵I-labeled ESF was 35.87 min for the rapid phase and 10.25 hr for the slow phase. The half-time disappearances of the unlabeled ESF for the rapid and slow phases were 32.39 min and 7.98 hr, respectively. The T1/2 values of the ¹²⁵I-labeled ESF and the unlabeled ESF are not significantly different.