Comparative Behavior of I 131 and C 14 Labelled Albumin in Plasma of Man. ∗

Abstract

Conclusion

1) Rapid incorporation of C¹⁴ into circulating albumin occurs following intravenous administration of glycine 2-C¹⁴ in man. The maximum C¹⁴ activity occurs at about 24 hours, and is followed by a loss of C¹⁴ albumin from the plasma which consists of a rapid exponential component with a half-time of about 3 days and a slow exponential component with a half-time of 28 to 39 days. 2) I¹³¹ trace iodinated albumin studied concurrently in the same patients leaves the plasma after extravascular equilibration at a rate that is more than twice as fast as the bio-synthetically C¹⁴ labelled albumin. (Half-time of 12 to 13 days.) 3) Difference in behavior between I¹³¹ and C¹⁴ albumin suggests that introduction of I¹³¹ into albumin significantly alters the metabolic behavior of the albumin.