Vectorial bicarbonate transport by Par-C10 salivary cells
Summary
Par-C10 cells, a rat parotid acinar line, secrete bicarbonate (HCO3-) via mechanisms involving Na+/H+ exchange and anion exchange. This provides a model for understanding salivary fluid secretion.
Area of Science:
- Physiology
- Cell Biology
- Gastroenterology
Background:
- Salivary glands secrete bicarbonate-rich fluid crucial for the upper gastrointestinal tract's neutral environment.
- The precise molecular mechanisms governing salivary bicarbonate secretion remain incompletely understood.
Purpose of the Study:
- To investigate the capacity of polarized Par-C10 rat parotid acinar cell monolayers to transport and secrete bicarbonate (HCO3-).
- To elucidate the molecular players involved in regulating intracellular pH and vectorial bicarbonate secretion in this cell line.
Main Methods:
- Utilized short-circuit current measurements to assess transepithelial electrolyte movement.
- Employed microfluorometry with BCECF to measure intracellular pH (pHi) changes.
- Grew Par-C10 cells on Transwell membranes to form polarized monolayers.
Main Results:
- Polarized Par-C10 monolayers exhibited vectorial anion secretion stimulated by ATP and forskolin.
- Secretion was partially dependent on NKCC and bicarbonate ions, with evidence of Na+/H+ exchange, Na+-HCO3- cotransport, and basolateral anion exchange.
- ATP and forskolin stimulated bicarbonate efflux, and acid loading recovery was sensitive to H2DIDS, indicating anion exchange activity.
Conclusions:
- Par-C10 cells demonstrate transepithelial transport sensitive to Ca2+ and cAMP.
- Key mechanisms identified include Na+/H+ exchange, Na+-HCO3- cotransport, and basolateral anion exchange, all contributing to pH regulation and bicarbonate secretion.
- The Par-C10 cell line serves as a valuable model for studying the molecular basis of salivary bicarbonate secretion.
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