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Characterization and Ca 2+ Requirement of Histamine‐Induced Catecholamine Secretion in Cultured Bovine Chromaffin Cells
Author(s) -
Goh Yasumasa,
Kurosawa Atsushi
Publication year - 1991
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 - 10.1111/j.1471-4159.1991.tb08286.x
Subject(s) - histamine , secretion , extracellular , medicine , catecholamine , endocrinology , chromaffin cell , calcium , fura 2 , stimulation , chemistry , intracellular , adrenal medulla , biology , biophysics , biochemistry , cytosol , enzyme
The stimulation of cultured bovine chromaffin cells with histamine induced a continuous catecholamine secretion (EC 50 = 3 × 10 −7 M ) via the H 1 receptor, in addition to an initial catecholamine burst due to a nonspecific stimulatory effect at higher doses (≥10 −4 M ). The continuous secretion showed little desensitization and lasted for more than 1 h. In fura‐2‐loaded cells, the stimulation with histamine evoked a transient rise of intracellular free Ca 2+ concentration ([Ca 2+ ] i ) which lasted only for a few minutes and was followed by a sustained [Ca 2+ ] i rise which continued for more than 20 min. The addition of an activator for the L‐type voltage‐sensitive Ca 2+ channel, i.e., Bay K 8644 (1 μ M ), facilitated the sustained [Ca 2+ ] i rise, as well as the secretion, whereas the addition of relatively high concentrations of Ca 2+ ‐channel blockers (10 μ M ) suppressed the sustained [Ca 2+ ] i rise and part of the secretion. Removal of extracellular Ca 2+ completely abolished continuous secretion and sustained [Ca 2+ ] i rise. When the external Ca 2+ level was elevated, both sustained (Ca 2 ] i rise and continuous secretion were enhanced in a similar Ca 2+ ‐dependent manner, showing saturation with around 1–3 m M Ca 2+ . This Ca 2+ dependence was clearly different from that observed with high K + and nicotine, which is mediated by the L‐type Ca 2+ channel, in which the responses showed little or no saturation when the Ca 2+ level was increased. The results indicate that stimulation with histamine induces a continuous secretion via the H 1 receptor, in addition to a transient and nonspecific secretion at higher doses. At least part of the continuous secretion is induced by a sustained [Ca 2+ ] i rise due to the continuous Ca 2+ influx through Ca 2+ channels. These channels are sensitive to dihydropyridines, but do not appear to be identical to the L‐type voltage‐sensitive Ca 2+ channel.