Proton efflux from rat intestinal basal-lateral membrane vesicles is stimulated by ATP and Na+

1. ATP-stimulated 22Na uptake and 14C-methylamine efflux were studied in inside-out rat intestinal basal-lateral membrane vesicles (BLMV). 2. Uptake of 22Na by basal-lateral membrane vesicles was stimulated by addition of ATP and by an acidic vesicle interior. 3. Efflux of 14C-methylamine was stimulated by ATP and Na+. 4. 14C-methylamine efflux was not influenced by vanadate or amiloride by themselves but was inhibited by the presence of both agents. 5. These data are consistent with a basal-lateral proton translocation mechanism which may be responsible for alkalinization of the lateral intercellular space and implicates the Na+-pump in this mechanism.