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Intracellular Ca requirements for stimulus-secretion coupling in parietal cell
P A Negulescu1, W W Reenstra, T E Machen
1Department of Physiology-Anatomy, University of California, Berkeley 94720.
The American Journal of Physiology
|February 1, 1989
Summary
Cytosolic free calcium (Cai) is crucial for carbachol-stimulated acid production in parietal cells. Histamine also shows some Cai dependence, while DBcAMP-stimulated secretion is independent of Cai levels.
Area of Science:
- Physiology
- Cell Biology
- Gastroenterology
Background:
- Parietal cells are responsible for gastric acid production.
- Cytosolic free calcium (Cai) is a key intracellular messenger.
- Secretagogues like carbachol and histamine stimulate acid secretion through various pathways.
Purpose of the Study:
- To investigate the role of Cai in parietal cell acid production stimulated by carbachol, histamine, and DBcAMP.
- To determine if Cai is a necessary signal for acid secretion induced by different secretagogues.
Main Methods:
- Microfluorimetry using fura-2 to measure Cai in single rabbit gastric parietal cells.
- Monitoring acid production via [14C]aminopyrine (AP) accumulation in gastric glands.
- Utilizing the calcium chelator BAPTA-AM to attenuate Cai increases.
Main Results:
- Carbachol dose-dependently increased Cai and AP accumulation, with BAPTA-AM significantly inhibiting both.
- Histamine caused minor Cai increases but its stimulated AP accumulation was partially inhibited by BAPTA-AM.
- DBcAMP did not affect Cai, and its stimulated AP accumulation was unaffected by BAPTA-AM.
Conclusions:
- Carbachol-stimulated acid secretion is dependent on increased Cai.
- Histamine-stimulated acid secretion exhibits partial Cai dependence, suggesting involvement of both Cai-dependent and independent pathways.
- DBcAMP-stimulated acid secretion is independent of Cai, indicating the existence of distinct signaling pathways in parietal cells.