Intestinal electrogenic HCO3- absorption localized to villus epithelium.

Isolated segments of jejunum from Amphiuma absorb HCO3+ electrogenically by a process sensitive to acetazolamide. Using a tissue chamber of special design which permits isolation of villus or intervillus epithelium the transepithelial electrical potential (psi ms) of each region was measured. The serosa-negative psi ms generated by the villus epithelium was more negative than that of the intervillus and exhibited greater sensitivity to acetazolamide. Both regions were responsive to other agents which alter epithelial ion transport. The results indicate that intestinal HCO3- absorption is localized predominantly within cells lining the villus epithelium.