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The mode of action of caffeine on catecholamine release from perfused adrenal glands of cat
Author(s) -
Yamada Yutaka,
Nakazato Yoshikazu,
Ohga Akira
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb12603.x
Subject(s) - caffeine , endocrinology , medicine , hexamethonium , catecholamine , chemistry , extracellular , egta , secretion , ouabain , stimulation , calcium , adrenal medulla , acetylcholine , perfusion , biology , sodium , biochemistry , organic chemistry
1 Adrenaline and noradrenaline secretion induced by caffeine was investigated in the perfused cat adrenal glands. 2 Caffeine (10–80 m m ) caused a dose‐dependent increase in both adrenaline and noradrenaline secretion when applied for 1 min and 10 min after replacing Ca 2+ with 10 −5 m EGTA in the perfusion solution. The ratio of adrenaline to noradrenaline was about 1:1. Mg 2+ and/or Ca 2+ inhibited the response to caffeine. 3 When caffeine (40 m m ) was repeatedly applied in the absence of extracellular Ca 2+ , the secretory response almost disappeared but only at the second challenge with caffeine. However, the response was partially restored after readmission of Ca 2+ (2.2 m m ) and was augmented after the readmission of Ca 2+ with ouabain (10 −5 m ). 4 Caffeine‐induced secretion of adrenaline and noradrenaline increased with the increase in the preloaded concentration of Ca 2+ and attained a maximum at 16 mM Ca 2+ . 5 During perfusion with Ca 2+ ‐free Locke solution containing hexamethonium (10 −3 m ), acetylcholine (10 −4 m ) caused increases in both adrenaline and noradrenaline secretions with a ratio of about 1:2. The secretory responses were partially inhibited by preceding stimulation with exposure to caffeine (80 m m ). 6 These results suggest that caffeine mobilizes Ca 2+ from an intracellular storage site that may not be entirely the same as that linked to muscarinic receptors, and causes an increase in both adrenaline and noradrenaline secretion from cat adrenal chromaffin cells.