Volume-sensitive K transport in human erythrocytes.

Abstract

Studies have been carried out on human erythrocytes to examine the alterations of K transport induced by swelling or shrinking the cells by osmotic and isosmotic methods. Hypotonic swelling of erythrocytes (relative cell volume, 1 .20) resulted in a striking, four-to fivefold augmentation in the ouabain-resistant K influx over the value obtained at a normal cell volume . Shrinking the cells in hypertonic media resulted in a small but statistically significant reduction in K influx . Three different methods of varying cell volume gave similar results. These include the addition of sucrose and of NaCI to hypotonic media and the isosmotic (nystatin) method . The major fraction of the K influx in swollen cells is specific in its requirement for CI or Br and is not supported by thiocyanate, iodide, nitrate, methylsulfate, or acetate. Bumetanide (0

Platelet-derived growth factor regulates K-Cl cotransport in vascular smooth muscle cells

“…However, in some of the experiments reported in this study, the basal Rb influx in sulfamate was higher than in Cl under certain experimental conditions. The absence of a basal Cl-dependent flux has been reported before in different cell types and species and with different techniques used to determine K-Cl COT activity (1,16,24,30). The reason for the lack of basal Cl-dependent flux under certain experimental conditions is not clear at this point and is under investigation.…”

Deficiency of Src family kinases Fgr and Hck results in activation of erythrocyte K/Cl cotransport.

“…Recently, models describing the mechanisms of regulation and kinetic properties of the K/Cl cotransporter have been proposed (13)(14)(15)(16)(17)(18). These models highlighted the importance of a dephosphorylation/phosphorylation cycle in regulating K/Cl cotransport activity as demonstrated by studies with inhibitors of serine/threonine protein phosphatases or protein kinases.…”

A mathematical model of the volume, pH, and ion content regulation in reticulocytes. Application to the pathophysiology of sickle cell dehydration.

“…The ion traffic across reticulocyte membranes must therefore remain balanced as it declines with maturation. The main ion transporters identified thus far in mammalian reticulocytes include the sodium pump (6, 7) and a ouabain-and bumetanide-insensitive, pH-and volume-sensitive K:Cl cotransport (6,(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19).…”