Effect of gossypol on erythrocyte membrane function: specific inhibition of inorganic anion exchange and interaction with band 3

The effects of gossypol on membrane functions of the human erythrocyte were studied. Gossypol (1 0 M) had no effect on spontaneous hemolysis, osmotic fragility, cell volume, cholines-terase activity, hexose transport, ouabain-sensitive inorganic cation transport, ouabain-insensitive inorganic cation transport and nucleoside transport. Conversely, 1 0 M gossypol inhibited inorganic anion transport by approximately 90 % for three differ-ent substrates, i.e., phosphate, sulfate and chloride. Inhibition of inorganic anion transport was specific as 1 0 M gossypol had no effect on the eight aforementioned membrane-related func-tions of the human erythrocyte. Inhibition of inorganic anion transport was characterized using sulfate as the substrate and had the following features: 1) it was potent, with a K, of approx-imately 3 tiM; 2) it was rapid, with onset occurring in <1 mm; 3