Potassium fluxes in the rat reticulocyte. Ouabain sensitivity and changes during maturation.
K+ turnover is markedly enhanced in the rat reticulocyte, both influx and efflux rates being increased by factors of approximately 3 over the corresponding rates in adult cells. These accelerated fluxes are observed despite the absence of any appreciable change in intracellular K+ concentration during the course of maturation. Qualitative characteristics of the active transport process for K+ influx appear to be identical in reticulocytes and mature erythrocytes with regard both to K+ sensitivity, and to ouabain sensitivity as a function of external K+ concentration. The number of ouabain binding sites per unit volume of cells, however, is increased by a factor of approximately three in the reticulocyte and thus correlates well with the observed degree of enhancement of active K+ influx in these cells. Half-maximal rates of ouabain-sensitive K+ influx are observed at external K+ concentrations well below 1 mM for both reticulocytes and mature erythrocytes. It is concluded that the enhanced rate of K+ accumulation in the reticulocyte can be quantitatively attributed to an increased number of pump units which are qualitatively identical to those in the mature cell, and which function at a near-maximal rate at the ambient K+ concentration present in normal rat plasma.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D007700:Kinetics; D008297:Male; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D012156:Reticulocytes / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000097:blood; D013045:Species Specificity; D014422:Turkeys
D006454:Hemoglobins; D010042:Ouabain; D012964:Sodium; D011188:Potassium