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Regulation of intracellular ph in culture bovine retinal pigment epithelial cells


, : Regulation of intracellular ph in culture bovine retinal pigment epithelial cells. Pfluegers Archiv European Journal of Physiology 411(1): 47-52

Regulation of intracellular pH (pHi) in bovine retinal pigment epithelium (RPE) was investigated in cell culture, pHi was measured using the pH-sensitive absorbance of intracellulary trapped 5 (and 6)-carboxy-dimethylfluorescein (CDMF). (1) Regulation of pHi after induction of an acid load by removal of NH4Cl could be blocked either totally by removal of extracellular sodium, or subtotally (about 90%) by application of amiloride (1 mmol/l). Additional flux measurements revealed a dose-dependent, amiloride-sensitive 22Na+-uptake into Na+-loaded cells. Both results suggest the presence of a Na+/H+ antiport. (2) When alkalinization of the cells was induced by preincubation with 50 mmol/l acetate in HCO3--Ringer's and subsequent removal of the weak acid, the following regulation was dependent on the presence of extracellular chloride. This process could be blocked with DIDS (1 mmol/l), suggesting the presence of a Cl-/HCO3- exchange mechanism. (3) We found no evidence for a Na+ HCO3--cotransport, which had been postulated to be present in RPE by others. We conclude that two processes are involved in regulation of pHi in RPE: A Na+/H+ antiport responsible for recovery of pHi from acid load, and a DIDS-sensitive Cl-/HCO3- exchange mechanism responsible for recovery of pHi after alkalinization.

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Accession: 006288861

PMID: 2832823

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