Simultaneous Estimation of Plasma Volume, Red Cell Volume and Thiocyanate Space in Unanesthetized Normal and Splenectomized Rats

Abstract

A method for simultaneous estimation of plasma volume, red cell volume and thiocyanate space in unanesthetized rats utilizing a polyethylene catheter in the common carotid artery with T-1824, P³²-tagged red cells, and NaSCN was perfected and determinations were performed on 77 male albino rats. Determinations of plasma volume using T-1824 or I¹³¹-serum albumin in the same animal gave essentially identical results. Total blood volume was calculated as the sum of P³²-red cell volume and T-1824-plasma volume and was found to be 5.75 ml/100 gm body weight in normal rats and 5.61 ml/100 gm in splenectomized rats. There was a wide variation in the F_cell values of normal rats but little in splenectomized rats. This difference was highly significant and was attributed to the presence of the spleen. The average thiocyanate space was found to be 33.0 ml and 35.8 ml/100 gm in normal and splenectomized rats, respectively.