Using Confocal microscope system in human vaginal epithelial cell line VK2/E6E7 cells loaded with the pHdependent fluorescent probe Snarf-4F

external ATP（10~1 000 μmol/L） was proved to dosedependently induce pHi decrease. When adding ATP (200 μmol/L) to the extracellular buffer

it induced a rapid pHi decrease and the intracellular acidification was rapidly reversed upon removal of external ATP. These results show external ATP could induce the intracellular acidification of VK2/E6E7 cells.