Functional impairments of human red cells,induced by dehydroepiandrosterone sulfate

A study has been made on the incorporation of dehydroepiandrosterone sulfate (DHAS), one of the most abundant adrenal C-19 steroids, into human red cells, and of the resulting effects on red cell functions. 1. DHAS was incorporated into red cell membrane mainly by a partition mechanism: The apparent partition constant was small ([DHAS]cell/[DHAS]free = 1.34), indicating that DHAS in red cells would be easily removed by dilution. 2. At least part of the DHAS taken up was apparently bound to band 3 protein and thereby was able to inhibit the exchange of intracellular and extracellular SO4(2-) (Ki = 70 micro M). 3. Using a fatty acid spin label, it was established that the presence of DHAS in lipid bilayer of the membrane increased the acyl chain motion in the middle portion of the membrane. 4. DHAS induced echinocytosis of red cells. It is suggested that the increase in the viscosity of red cell suspension, the decreased deformability and the decrease in the deoxygenation rate of hemoglobin in the presence of DHAS probably reflect the presence of echinocytes. 5. In the presence of plasma proteins, the incorporation of DHAs into red cells was remarkably suppressed.