Pb 212 (ThB) Tracer Studies in Adult Beagle Dogs. ∗

Abstract

Summary

Beagle metabolism of short-lived Pb²¹² has been studied following intravenous injection, and after transfusion of blood cells tagged with Pb²¹² in vitro. The latter proved to be a satisfactory method to determine blood volume. When Pb²¹² was given intravenously, in vivo tagging of blood cells occurred. A maximum of 65% of the activity in cells was reached at 2 to 3 hours after injection, then Pb²¹² in blood cells decreased with a biological t_1/2 = 37 hours and an effective t_1/2 = 8.2 hours. The same decrease occurred after injection of in vitro tagged cells. In both experiments essentially all Pb²¹² decayed inside the dog. Half decayed in blood in the in vivo tagging experiment: 4′5 decayed in blood when tagging was done in vitro.