Effect of Dietary Protein Restriction on Plasma Volume, "Available (Thiocyanate) Volume" and Muscle Water

Hypoproteinemia induced in rats and dogs by protein-deficient diets was accompanied by a fall of the P.V. and “SCN” when expressed per unit of control weight and increased when expressed per unit of experimental weight. Thus, there was a decrease in the absolute extracellular volume, as measured by thiocyanate, in the presence of a “relative” extracellular hydration. The extracellular phase of muscle calculated on the basis of the muscle chloride content progressively increased as the plasma albumin decreased. This can be interpreted as indicating an accumulation of extracellular fluid accompanying a progressive hypoproteinemia. However, because of the observed decrease of the “SCN,” these observations appear better explained on the basis of a reduction in cellular mass without a large change in the absolute amount of extracellular fluid.