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Evidence for a dihydropyridine‐sensitive and conotoxin‐insensitive release of noradrenaline and uptake of calcium in adrenal chromaffin cells
Author(s) -
Owen P. Jane,
Marriott Deborah B.,
Boarder Michael R.
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.tb11933.x
Subject(s) - nitrendipine , dihydropyridine , conotoxin , calcium , voltage dependent calcium channel , chemistry , endocrinology , medicine , bradykinin , t type calcium channel , biophysics , biology , biochemistry , peptide , receptor , organic chemistry
1 It has been suggested that neuronal voltage‐sensitive calcium channels (VSCC) may be divided into dihydropyridine (DHP)‐sensitive (L) and DHP‐insensitive (N and T), and that both the L and the N type channels are attenuated by the peptide blocker ω‐conotoxin. Here the effects of ω‐conotoxin on release of noradrenaline and uptake of calcium in bovine adrenal chromaffin cells were investigated. 2 Release of noradrenaline in response to 25 m m K + , 65 m m K + , 10 n m bradykinin or 10 μ m prostaglandin E 1 was not affected by ω‐conotoxin in the range 10 n m ‐1 μ m . 3 45 Ca 2+ uptake stimulated by high K + and prostaglandin was attenuated by 1 μ m nitrendipine and enhanced by 1 μ m Bay K 8644; these calcium fluxes were not modified by 20 n m ω‐conotoxin. 4 With superfused rat brain striatal slices in the same medium as the above cell studies, release of dopamine in response to 25 m m K + was attenuated by 20 n m ω‐conotoxin. 5 These results show that in these neurone‐like cells, release may be effected by calcium influx through DHP‐sensitive but ω‐conotoxin‐insensitive VSCC, a result inconsistent with the suggestion that ω‐conotoxin blocks both L‐type and N‐type neuronal calcium channels.