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Effect of hyperosmolarity on extracellular acidification associated with catecholamine secretion evoked by barium in
P N Viglione1, C Gomez, J E Pinto
1Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Abstract:
1. The effects of the increase of osmotic strength on extracellular pH modifications produced during buffer-free, 5 mM Ba2+ stimulation was studied in decorticated perfused bovine adrenal glands. 2. A pronounced and reversible attenuation of the extracellular pH drop as well as of the release of catecholamines induced by Ba2+ was detected in glands exposed to a hyperosmotic (750 mOsm) perfusion fluid made up by the addition of NaCl. 3. Similar results were observed using sucrose as osmoticant instead of NaCl. 4. A progressive decline in both external acidification and secretory response to Ba2+ was found on gradually increasing the osmotic strength of the perfusion fluid. 5. These results provide additional evidence in favour of the existence of a close association between extracellular acidification and adrenomedullary secretion induced by buffer-free Ba2+.