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Decrease of extracellular pH associated with the secretion of catecholamines induced by barium in perfused bovine
J E Pinto1, P N Viglione, R P Rothlin
1Departamento de Fisiologia, Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Argentina.
General Pharmacology
|March 1, 1993
Summary
Barium (Ba2+) stimulation causes a pH drop and catecholamine release in adrenal glands. This effect lessens with repeated stimulation, suggesting protons regulate secretion.
Area of Science:
- Endocrinology
- Neuroscience
- Physiology
Background:
- Extracellular pH (pHe) can influence cellular function.
- Adrenomedullary secretion is a key endocrine and neural process.
Purpose of the Study:
- To investigate the impact of barium (Ba2+) stimulation on extracellular pH in bovine adrenal glands.
- To explore the role of proton release in regulating catecholamine secretion.
Main Methods:
- Studied decorticated, perfused bovine adrenal glands.
- Applied buffer-free 5 mM Ba2+ solutions and Locke solution at varying pH.
- Measured extracellular pH changes and catecholamine release.
Main Results:
- Ba2+ stimulation caused a significant, reversible drop in extracellular pH, coinciding with catecholamine release.
- Repeated Ba2+ stimulation led to diminished pH drops and attenuated secretory responses.
- D-600 (methoxyverapamil) antagonized both the secretory response and pH drop.
- Lowering extracellular pH reduced the secretory response to Ba2+.
Conclusions:
- Barium-induced adrenomedullary secretion is associated with proton release.
- These released protons may act as a local negative feedback mechanism, modulating secretion.