Distribution of Blood (Fe) and Plasma (I) Volumes of Rats Determined by Liquid Nitrogen Freezing

T^ has been no complete organ blood volume study for any animal, nor any definitive total body blood volume determination for the rat. Thus, an extensive study was undertaken to determine the normal red cell and plasma volumes of the whole rat and for each of its major organs or tissues. This study is a prerequisite to investigations concerned with the effect of various experimental procedures upon blood distribution in the rat. Kaliss and Pressman reported the plasma and blood volumes of a limited number of mouse organs, as determined with radioactive iodoproteins, but the given values varied considerably from animal to animal. These variations were attributed in part to variable blood loss during the process of dissection. Recently Friedman determined the plasma volumes for seven mouse organs utilizing I albumin as a plasma label. Hemorrhage and anaesthesia were avoided by freezing the mice in liquid nitrogen prior to dissection. Although several blood volume studies have been made for the rat, the results have been quite variable, ranging from 4.3 ml./lOO Gin., Griffith and Campbell; to 7.98 ml./lOO Gm, Beckwith and Chanutin. Using the Fe tagged cell method, Berlin and associates reported the blood volume of the rat to be from 3.63 to 5.81 ml./lOO Gm. and Sharpe, Culbreth and Klein reported a mean value of 4.95 ml./lOO Gm. The utilization of Fe cells probably provides