Measurement of Extracellular Fluid Volume and Blood Volume in Sheep

Abstract

Methods are described for the simultaneous measurement of extracellular fluid volume (ECFV) and plasma volume (PV) in sheep using dilution of 82Br (as sodium bromide) and l3lI-labelled ovine gamma globulin. Following injection of 82Br (100 }lCi), equilibrium in blood was reached after 3 h at which time only 4 % of the injected dose was in rumen water. The ECFV was measured as the mean Of the 2- and 3-h bromide space after correction for the relative water content of plasma, the Gibbs-Donnan factor and the loss of 82Br into red blood cells. l 3lI-labelled ovine gamma globulin (20 }lCi) was injected after the 3-h 82Br space was obtained and blood samples were taken at 10, 20, 30 and 40 min.