CL-/HCO3- EXCHANGE IN PLASMA-MEMBRANE VESICLES FROM CELLS OF SUGAR-BEET SUSPENSION-CULTURE

Using pH-sensitive probe acridine orange, addition of HCO3- to KCl-loaded plasmalemma vesicles from cell of sugar beet suspension culture was shown to lead to the alkalization of the intravesicular space. This effect was saturated at high [HCO3-] (K(m) = 5 mM). HCO3--dependent pH changes were not observed in the vesicles not containing Cl- ions. The rate of intravesicular alkalization was inhibited by 50% in the presence of 0.9-mu-M 4,4-diisothiocyanostilbene-2,2-disulfonic acid or 0.3 mM furosemide. These results led us to suggest the existence of Cl-/HCO3--antiporter in plasma membrane.