| pubmed-article:1335884 | pubmed:abstractText | BCECF, a cell-entrapable dye with a pH-sensitive fluorescence spectrum, was used to identify transport mechanisms contributing to pH homeostasis of cultured bovine lens epithelial cells. Cells from a spontaneously established lineage were grown on glass coverslips that fit diagonally in a standard curvette and intracellular pH (pHi) was measured. Under perfusion with a CO2-HCO3(-)-free medium (pH 7.45), pHi was 7.19 +/- 0.21 (mean +/- S.D., n = 94 cell preparations). Cell acidifications (pHi to 6.65, n = 8) induced by the 'NH(4+)-loading' method were rapidly followed by a Na(+)-dependent, amiloride-inhibitable pHi recovery. Introduction of a CO2-HCO3(-)-rich medium (pH 7.45) resulted in a small acidification (0.18 +/- 0.04 U, n = 16; P < 0.002) due to rapid CO2 entry and an ensuing slow alkalinization to a pHi near the control CO2-HCO3(-)-free value. Subsequent removal of Cl- resulted in a further alkalinization of 0.18 +/- 0.02 U (n = 13; P < 0.001). This Cl- effect was completely inhibited by the absence of Na+, but was insensitive to amiloride, suggesting the presence of a Na(+)-dependent Cl(-)-HCO3- exchanger. Consistent with this posit, the reintroduction of Na+ to cells perfused in the absence of the cation with a HCO3(-)-containing, amiloride-complemented solution resulted in a gradual recovery from the acidic pHi induced by the baseline conditions (n = 6). The amiloride-insensitive, Na(+)- and HCO3(-)-dependent recovery was completely inhibited in cells pre-incubated with DIDS.(ABSTRACT TRUNCATED AT 250 WORDS) | lld:pubmed |
