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Chromaffin cell; γ-Aminobutyric acid; Cytosolic Ca; Fura-2; Calcium channel; Bicuculline; Bovine adrenal medulla
Abstract:
Measurements of the cytosolic Ca concentration ([Ca]i) with the Ca-sensitive dye, fura-2, showed that in intact, but not in voltage-clamped, bovine chromaffin cells γ-aminobutyric acid (GABA, 10 μM) elicited a transient increase in [Ca]i. The Ca transient of intact cells was inhibited by bicuculline (20 μM), by removal of extracellular Ca or by treatment with the Ca channel blocker cobalt (2.5 mM), and enhanced by lowering the extracellular Cl. We conclude, that GABA elevates [Ca]i by inducing a GABAA-receptor-linked Cl current which depolarizes the cell membrane sufficiently to activate potential-operated Ca channels and cause Ca entry into the cell.
