Direct Determinations of Plasma, Cell, and Organ-Blood Volumes in Normal and Hypervolemic Mice

Abstract

Direct single and combined cell- and plasma-volume determinations were made on normal and polycythemic mice with p32-tagged red cells and I131-tagged plasma. These were prepared in the usual manner except that for the latter the unbound inorganic iodide was removed with an anion-exchange column. The data indicate that: (a) The Evans-blue volumes in mice are above the probably more correct I131-plasma volumes by a factor of 1.2 and in rabbits by a factor of 1.08. (b) The so-called mixing time of Evans blue is a withdrawal time of this dye by cells with affinity for it most of which are probably macrophages. (c) The cell volume calculations based on Evans-blue values are higher than those obtained by direct detns. with the p32 technic by a factor of 1.56 in normal and 1.51 in tumor-bearing mice tested, (d) The avg. body hematocrit in mice is approx. 0.88 times the venous hematocrit. (e) On the basis of these conversion values a calculation of all values can be made if only one technic is employed, (f) Hypervolemia caused by estrogen-secreting tumors is attributable to an almost selective plasma-volume rise while that with luteoma is due primarily to polycythemia and, to a lesser extent, to a plasma volume rise.