Distribution equilibria of sulfate in vitro between red blood cells and plasma

Abstract

Rabbit and dog blood was incubated in vitro in various gas mixtures with carrier-free Na2S35O4. The pH and the ratio of distribution of sulfate ion between red blood cells and plasma were determined. These ratios are pH dependent. The curve for these distribution ratios as a function of pH is lower than, but parallel to the curve of the square of the blood chloride ratios. This suggests that although the Gibbs-Donnan Law describes the change in sulfate ion distribution ration with changes in pH, there is significant binding of sulfate by plasma constituents. The rate constant for the penetration of radiosulfate into red blood cells incubated in vitro was found to be K = 0.045 ± 0.02/min. at pH 7.35 ± 0.05. The rate constant for the efflux of radiosulfate from Na2S35O4-labeled red blood cells into plasma was K = 0.06 ± 0.015/min. at pH 7.35 ± 0.05.