Abstract
We have previously shown that ileal villi exhibit Cl−/HCO3− exchange activity by microfluorometry and express at least three Cl−/HCO3− exchangers, i.e., Slc26a3, Slc26a6 and AE2, by RT-PCR. This study further characterized Cl−/HCO3− exchange activity. [Methods] Isolated villous tips from mouse ileum were loaded with BCECF and intracellular pH (pHi) was determined by microfluorometry on the stage of inverted microscopy. The samples were illuminated alternately at 440 and 500 nm, and the fluorosence was measured at 520∼570 nm through interference filter. HCO3−/CO2-buffered solution was used for superfusing the samples. [Results] The pHi was increased by removing Cl− from superfusing solution and recovered upon re-addition of Cl−. The pHi recovery upon re-addition of Cl was hardly suppressed by 300 μM DIDS, while it was inhibited by tenidap (10 μM, 40% inhibition). The rates of pHi increase and decrease upon Cl− removal and readdition, respectively, were not affected by the treatment of the sample with forskolin (10 μM). [Conclusion] These results suggest that Slc26a3 is mainly responsible for pHi change induced by Cl− removal protocol in villous tip cells. [Jpn J Physiol 55 Suppl:S85 (2005)]
