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Calcium Uptake and Catecholamine Secretion by Cultured Bovine Adrenal Medulla Cells
Author(s) -
Kilpatrick Daniel L.,
Slepetis Ruta J.,
Corcoran James J.,
Kirshner Norman
Publication year - 1982
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.1471-4159.1982.tb08647.x
Subject(s) - veratridine , ionomycin , adrenal medulla , calcium , catecholamine , endocrinology , medicine , chemistry , chromaffin cell , t type calcium channel , secretion , voltage dependent calcium channel , fura 2 , biophysics , biology , sodium , biochemistry , sodium channel , cytosol , organic chemistry , enzyme
The uptake of 45 Ca 2+ and secretion of catecholamines by primary cultures of adrenal medulla cells were studied. Nicotine, veratridine, potassium, and Ionomycin stimulate both the accumulation of 45 Ca 2+ and the secretion of catecholamines. Nicotinic antagonists block 45 Ca 2+ uptake induced by nicotine, tetrodotoxin blocks 45 Ca 2+ uptake induced by veratridine, and D600 blocks uptake induced by K + , nicotine, and veratridine, but not 45 Ca 2+ uptake or secretion induced by Ionomycin. The EC 50 for nicotine is 3 μ m for catecholamine secretion and 10 μ m for 45 Ca 2+ uptake, while the EC 50 S for veratridinestimulated uptake and secretion are approximately the same (75 μ m ). Kinetic studies show that the uptake of Ca 2+ is rapid and appears to precede the secretion of catecholamines, and that the rate of uptake declines rapidly. The uptake of 45 Ca 2+ and secretion of catecholamines stimulated by veratridine and 50 m m ‐K + show saturation kinetics with respect to external calcium concentrations at about 2 m m . On the other hand, the uptake of 45 Ca 2+ stimulated by nicotine does not become saturated at external calcium concentrations of 10 m m although the secretion of catecholamines reaches a maximum at external calcium concentrations of 2 m m . The data suggest that depolarizing agents such as veratridine and 50 m m ‐K + stimulate 45 Ca 2+ entry through voltage‐sensitive calcium channels, while nicotinic agonists stimulate calcium entry through the acetylcholine receptor ion channels as well as through voltage‐sensitive calcium channels.