Oxygen sensitivity of red cell membrane transporters revisited

In this paper, we provide an update on O-2-dependent membrane transport in red cells. O-2-sensitive membrane transport was compared in nucleated (chicken) and enucleated (human) red cells, to investigate effects on organic (glucose transporter [GLUT]) and inorganic (K+-Cl- cotransporter [KCC]Na+-K+-2Cl(-) cotransporter [NKCC]) transporters, to study the response of so-called "housekeeping" transporters (Na+/K+ pump and anion exchanger [AE]) and, finally, to compare O-2 sensitivity in normal human red cells with those from sickle cell patients. The Na+/K+ pump showed no change in activity between oxygenated and deoxygenated cells in any of the samples. KCC in normal human red cells had the greatest O-2 sensitivity, being stimulated some 20-fold on oxygenation. It was more modestly stimulated by O-2 in chicken red cells and HbS cells. By contrast, NKCC was stimulated by deoxygenation in all cases. GLUT showed little response to O-2 tension, other than a small stimulation in deoxygenated chicken red cells. Finally, AE I was stimulated by oxygenation in HbA cells, but this stimulation by O-2 was absent in HbS cells and pink ghosts prepared from HbA cells. The significance of these findings is discussed. (C) 2003 Elsevier B.V. All rights reserved.