Effect of Internal Emitters on Red Cell and Plasma Volumes of Beagle Dogs. ∗

Summary

Simultaneous red cell and plasma volumes have been measured with Cr⁵¹ and I¹³¹ in control beagle dogs and dogs with internally deposited radioisotopes. The reliability of the method is discussed. In isotope treated anemic dogs the venous hematocrit tended to be higher than the total body or true hematocrit but more accurately reflected red cell volume changes than in controls. Plasma volume did not change to account for this relative increase in venous hematocrit. It is postulated that this relatively high venous hematocrit probably represents a shift of red cells into large caliber veins.