The chloride transport induced by triaklyl-tin compound across erythrocyte membrane

The effect of tripropyl-tin chloride on anion permeability was studied using red cells previously treated with a covalent binding inhibitor 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) to inhibit completely and irreversibly the natural anion transport system. It was demonstrated that the tin compound can mediate chloride-hydroxide and chloride-chloride exchanges across the "impermeabilised" erythrocyte membrane. In the non hemolytic range, the rate of exchange increased with the concentration of the tin compound in a non linear fashion, and no saturation effect was seen. The temperature profile of the chloride self exchange induced by tripropyl-tin was studied and the apparent activation energy found was 29 Kcal/mol. The tripropyl-tin chloride cannot mediate a chloride-bicarbonate exchange. Because of this discriminatory effect between hydroxide and bicarbonate, the tin compound can be useful in certain experimental conditions as seen for the study of the anion "carrier" of the red cell membrane ("cousin, J.L., Motais, R. and Sola, F. (1975) J. Physiol. Lond. 253, 385-399).