Abstract
<Introduction>Slc26 family and AE family are distinct structurally, but both mediate anion exchange at the plasma membrane. The purpose of this study is to identify, in small intestinal enterocytes, anion exchangers which belong to Slc26 family and AE family by intracellular pH (pHi) measurements and by using RT-PCR.<Method> Top parts of villus were cut from mouse ileum, and loaded with BCECF-AM. Fluorescent measurement was performed on the stage of an inverted microscope. The samples were illuminated alternately at 440 and 500 nm, and the fluoresence was measured at 520-570 nm through interference filter. The pHi was calibrated by the nigericin-high K+ method.<Result and Discussion> In HCO3−/CO2 buffer enterocytes were alkalized by removal of Cl− and recovered by restoration of Cl−, whereas in HCO3−/CO2-free buffer the alkalization induced by Cl− removal was not observed. This indicated that enterocytes had an activity of Cl−/HCO3− exchange. The pHi recovery from alkalization induced by Cl− removal was observed by addition of Br−, I−, F−, NO3−, or SO42-. The pHi recovery by all attempted anions were smaller than that by Cl−. In addition, SO42- did not recovered pHi until baseline while others did. These results suggested that there were more than two functionally distinct Cl−/HCO3− exchangers in mouse ileal enterocytes, one accepting SO42- in place of Cl− (thus, probably a member of Slc26 family) and the other not. In additional experiments, we confirmed the expression of Slc26a3, Slc26a6 and AE2 in mouse ileal enterocyte by RT-PCR analysis. [Jpn J Physiol 54 Suppl:S86 (2004)]
