EFFECTS OF SULFHYDRYL INHIBITION ON RED BLOOD CELLS. II. STUDIES IN VIVO*

Abstract

Red cells of human or rat exposed in vitro to sublytic amounts of the sulfhydryl inhibitors N-ethylmaleimide (NEM) and p-mercuri-benzoate (PMB) are nonviable in vivo. Loss of viability is related to the inhibition of membrane sulfhydryl groups but is unrelated per se to intracellular sulfhydryl levels or to the over-all rate of cellular glycolysis. An association, however, does exist between the ability of these cells to maintain cation gradients in vitro and their ability to survive in vivo. Red cells treated with small doses of sulfhydryl inhibitor were of normal appearance and fragility and slowly lost K+; such cells on reinjection were trapped by the spleen with remarkable selectivity. Sequestration does not appear to depend upon changes in red cell shape, increased agglutinability, or erythrophagocytosis. After their sequestration in the spleen these red cells showed a progressive increase in osmotic fragility. Larger doses of inhibitor caused Na+ and water ingress, spherocytosis, and a more rapid hepatic, as well as splenic, sequestration. Since inhibition of high-energy phosphate metabolism in red cells by arsenate caused a delayed, slow destruction of red cells in vivo, and since cessation of anaerobic glycolysis and K+ depletion in red cells by exposure for several hours to Fl- had comparatively little effect upon their subsequent survival, it is concluded that membrane sulfhydryl groups are uniquely important to cell viability. It is suggested that a loss of membrane sulfhydryl activity may be the decisive hemolytic event common to a number of processes, including the Heinz body anemias and normal cellular aging.