Interaction between Na ions and the Cl/HCO3 exchanger in basolateral membranes from rat jejunum.

The jejunal basolateral Cl/HCO3 exchanger is modulated by two Na-dependent regulatory sites located on the inner and outer membrane surfaces. The aim of this work was to focus on the interaction between the anion exchanger and intracellular or extracellular sodium. Uptake studies, performed using basolateral membrane vesicles, provided kinetic parameters as a function of outside or inside Na concentration. The intracellular Na-sensitive modifier site seems to be primarily involved in the modulation of the Cl/HCO3 exchanger.