Chloride mediated inhibition of the phosphate and the sulfate transport by dipyridamole in human erythrocyte ghosts.

The inhibition of the unidirectional phosphate and sulfate flux in human erythrocyte ghosts by dipyridamole has been investigated. The inhibition of the phosphate and the sulfate flux is mediated by chloride. At zero chloride, dipyridamole was found to be completely ineffective. At 10 mM chloride, dipyridamole acts as a noncompetitive inhibitor of the phosphate and the sulfate flux and elicits an up to 95% inhibition of the phosphate and the sulfate transport. The results of our studies provide strong evidence for a cooperative binding of chloride and of dipyridamole to the non-protonated form of the band 3 membrane domain.