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HCO3-dependent pHi regulation in tracheal epithelial cells
1Department of Molecular and Cell Biology, 231 LSA, University of California, Berkeley, CA 94720-3200, USA.
Pflugers Archiv : European Journal of Physiology
|July 1, 1996
Summary
Bovine tracheal epithelial cells regulate intracellular pH (pHi) using bicarbonate-dependent mechanisms. The cystic fibrosis transmembrane conductance regulator (CFTR) likely mediates bicarbonate influx, influencing periciliary fluid pH.
Area of Science:
- Cell Physiology
- Epithelial Transport
- Biochemistry
Background:
- Intracellular pH (pHi) regulation is crucial for cellular function.
- Bovine tracheal epithelial cells play a role in airway surface liquid homeostasis.
Purpose of the Study:
- To investigate the mechanisms of pHi regulation in cultured bovine tracheal epithelial cells.
- To identify the transporters and channels involved in bicarbonate (HCO3)-dependent pHi recovery.
Main Methods:
- Microspectrofluorimetry using BCECF to measure pHi recovery rates after acidification.
- Utilized various solutions (HCO3-free, Na-free, Cl-free) and inhibitors (amiloride, bafilomycin, SCH28080, H2DIDS, DNDS, DPC).
- Manipulated membrane potential by altering extracellular potassium concentration.
Main Results:
- Na-dependent mechanisms contributed to basal pHi recovery.
- A significant HCO3-dependent, Na-independent pHi recovery was observed.
- This recovery was blocked by DPC, suggesting involvement of CFTR or similar channels.
- H,K-ATPase showed minor contribution, while H-ATPases did not significantly impact pHi recovery.
Conclusions:
- Bicarbonate influx via CFTR channels is a major pathway for pHi recovery in these cells.
- CFTR may also mediate bicarbonate secretion, contributing to periciliary fluid pH regulation.
- These findings highlight the role of epithelial ion transport in maintaining airway surface liquid pH.