Anion channel blockade: effects upon erythrocyte membrane calcium response.

The influx of small amounts of calcium into normal human red cells adversely affects cellular metabolism, shape, ion and water content, and deformability. Because restriction of cation (potassium) efflux moderates these deleterious effects of Ca++ influx, we investigated the possibility that inhibition of anion permeability might be similarly beneficial. Human red cells were treated with 4,4'-diisothiocyano-2,2'-stilbene disulfonate (DIDS), which reacts preferentially with external sites on the transmembrane protein, band 3, and specifically inhibits inorganic anion transport. DIDS-treated and control cells were then exposed to the ionophore A23187 and Ca++. We find that DIDS treatment blocks Ca++-induced K+ and water loss and diminishes changes in osmotic fragility and cellular elasticity. Furthermore, DIDS reduces the "trapping" of hemoglobin by red cell membranes and increases the apparent affinity of the cell membrane for glyceraldehyde-3-phosphate dehydrogenase.