Effects of sulfhydryl reagents on the anti-sickling activity of some membrane-interacting compounds

Under deoxygenated conditions (PO2 = 0 mmHg), sulfhydryl reagents such as N-ethylmaleimide and iodoacetamide had no effect on sickling, but they did inhibit the anti-sickling activity of chlorpromazine. At the same concentration, these sulfhydryl reagents inhibited the cup formation of chlorpromazine in an oxygenated state (PO2 = 143 mmHg). This supports our previous finding that the anti-sickling effect of membrane-interacting compounds is related to their ability to form a cup-shaped red cell.