The passive K influx in low K(LK) red blood cells of sheep saturates with increasing external K concentration, indicating that this mode of transport is mediated by membrane-associated sites. The passive K influx, iMLK, is inhibited by external Na. Isoimmune anti-L serum, known to stimulate active K transport in LK sheep red cells, inhibits iMLK about twofold. iMLK is affected by changes in intracellular K concentration, [K]i, in a complex fashion: increasing [K]i from near zero stimulates iMLK, while further increases in [K]i, above 3 mmol/liter cells, inhibit iMLK. The passive K influx is not mediated by K-K exchange diffusion. The effects of anti-L antibody and [K]i on passive cation transport are specific for K: neither factor affects passive Na transport. The common characteristics of passive and active K influx suggest that iMLK is mediated by inactive Na-K pump sites, and that the inability to translocate Na characterizes the inactive pumps. Anti-L antibody stimulates the K pump in reticulocytes of LK sheep. However, anti-L has no effect on iMLK in these cells, apparently because reticulocytes do not have the inactive pump sites which, in mature LK cells, are a consequence of the process of maturation of circulating LK cells. The results also indicate that anti-L alters the maximum velocity of both active and passive K fluxes by converting pumps sites from a form mediating passive K influx to an actively transporting form.
Article| December 01 1976
Passive potassium transport in LK sheep red cells. Effects of anti-L antibody and intracellular potassium.
P B Dunham
Online Issn: 1540-7748
Print Issn: 0022-1295
J Gen Physiol (1976) 68 (6): 567–581.
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P B Dunham; Passive potassium transport in LK sheep red cells. Effects of anti-L antibody and intracellular potassium.. J Gen Physiol 1 December 1976; 68 (6): 567–581. doi: https://doi.org/10.1085/jgp.68.6.567
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