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Na-HCO3 cotransport in rabbit parietal cells
1Department of Physiology-Anatomy, University of California, Berkeley 94720.
The American Journal of Physiology
|September 1, 1989
Summary
Rabbit parietal cells use a sodium- and bicarbonate-coupled transporter to recover intracellular pH (pHi) after acid loading. This mechanism is crucial for maintaining cellular homeostasis in these cells.
Area of Science:
- Cell Physiology
- Gastroenterology
- Biochemistry
Background:
- Parietal cells are crucial for gastric acid secretion.
- Maintaining intracellular pH (pHi) is vital for cellular function.
- Acid loading can disrupt normal parietal cell function.
Purpose of the Study:
- To investigate the mechanisms of intracellular pH recovery in rabbit parietal cells after acid loading.
- To determine the role of sodium (Na+) and bicarbonate (HCO3-) in pHi regulation.
- To identify the specific transporters involved in pHi homeostasis.
Main Methods:
- Utilized microspectrofluorometry to measure intracellular pH (pHi) in individual rabbit parietal cells.
- Induced intracellular acidification using ammonium chloride (NH4Cl) or by lowering external pH.
- Employed amiloride to block Na+-H+ exchange and assess alternative recovery pathways.
Main Results:
- Acid loading decreased pHi from 7.1 to approximately 6.6.
- In the presence of amiloride, pHi recovery required both Na+ and HCO3-.
- This Na+- and HCO3-dependent recovery was inhibited by H2 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and occurred in both Cl-containing and Cl-free solutions.
Conclusions:
- Resting rabbit parietal cells possess a Na+-HCO3- cotransporter.
- This cotransporter functions as a base loader, essential for pHi recovery under physiological conditions.
- The Na+-HCO3- cotransporter plays a significant role in maintaining acid-base balance in parietal cells.