Characteristics of anion transport in cat and dog red blood cells

Summary Self-exchange of chloride and sulfate in dog and cat red cells has been measured under equilibrium conditions. The rates of efflux for these anions are approximately twofold higher in dog compared to cat red blood cells. Although the rates differ, the anion exchange systems of these two red cell types exhibit many common properties. The dependence of³⁵SO₄ efflux on the intracellular SO₄ concentration, the pH dependence and the inhibition of³⁵SO₄ efflux by Cl and SITS are almost identical in dog and cat red cells. Nystatin treatment was used to study the dependence of³⁶Cl efflux on internal Cl. Chloride efflux exhibits saturation in both cell types with dog red cells possessing a higherV _max andK _1/2 than cat red cells. The number of anion transport sites was estimated by extrapolation to the number of molecules of dihydro DIDS (H₂DIDS, where DIDS is 4,4-diisothiocyano-2,2 stilbene-disulfonic acid) which were bound at 100% inhibition of transport. The results indicate that either the turnover numbers for anion transport differ in dog, cat, and human red cells or that there is heterogeneity in the function of the membrane components which bind H₂DIDS.