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Rundown of Secretion After Depletion of Intracellular Calcium Stores in Bovine Adrenal Chromaffin Cells
Author(s) -
Pan ChienYuan,
Fox Aaron P.
Publication year - 2000
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2000.0751132.x
Subject(s) - thapsigargin , exocytosis , intracellular , chromaffin cell , calcium in biology , secretion , calcium , microbiology and biotechnology , endocrinology , stimulation , medicine , depolarization , adrenal medulla , biology , chemistry , catecholamine
In this study, the relationship between intracellular calcium stores and depolarization‐evoked stimulation was examined in bovine chromaffin cells, using changes in membrane capacitance to monitor both exocytosis and endocytosis. Cells were voltage‐clamped using the perforated whole‐cell patch configuration to minimize alterations in intracellular constituents. Control cells exhibited reproducible secretory responses each time the cell was stimulated. However, the same stimulation protocol elicited progressively smaller secretory responses in cells where their intracellular calcium store was emptied by thapsigargin. Transient elevation of the intracellular calcium concentration with a brief histamine treatment enhanced subsequent secretory responses in control but not in thapsigargin‐treated cells. A series of depolarizations to ‐20 mV, which allowed small amounts of Ca 2+ influx but which by itself did not trigger catecholamine secretion, enhanced subsequent exocytosis in both control and thapsigargin‐treated cells. Caffeine‐pretreated cells exhibited a rundown in the secretory response that was similar to that produced by thapsigargin. These results suggest that brief elevations of [Ca 2+ ] i could enhance subsequent secretory responses. In addition, the data suggest that intracellular calcium stores are vital for the maintenance of exocytosis during repetitive stimulation.