THE BIOLOGICAL DECAY CURVE OF P32 TAGGED ERYTHRO-CYTES. APPLICATION TO THE STUDY OF ACUTE CHANGES IN BLOOD VOLUME 1

Abstract
Following intra-ven. admn. of p32 labeled erythrocytes, a semilogarithmic plot of the radioactivity per unit volume of whole blood as a function of time is a straight line for at least 48 hrs. in human subjects with unchanging blood volumes. The biological half-lives in 18 expts. ranged from 12-39 hrs. This exponential relationship permits the detn. of serial whole blood and plasma volumes with an error of 2-3%. It may therefore be used to quantitate rapid changes in these volumes without requiring reinjn. technics. The observed alterations in blood volume produced by digitalis, mercurial diuretics, positional changes and human serum albumin infusion are briefly discussed.