Simultaneous measurement in dogs of plasma volume with I131 human albumin and T-1824 with comparisons of their long-term disappearance from the plasma.

vv HEN used for measurement of plasma volume, bovine plasma proteins (I) and dog hemoglobin (2) have the same initial volume distribution as the dye, T-1824, which in the bloodstream combines preferentially with albumin (3). In regard to simultaneous comparisons in dogs of plasma volume measured with T-1824 and human albumin labeled with the 1131 isotope, there are conflicting reports (cf. 4-7). We here show results confirming those studies in man and dog in which agreement was found (6-9). It will be seen also that although loss rates of T-1824 and I131-human albumin are similar during the first hour, the long term losses of these two substances are distinctly different in. dogs, as previously reported by Wasserman and Mayerson (I 0).