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Mobilization of Inositol 1,4,5‐Trisphosphate‐Sensitive Ca 2+ Stores Supports Bradykinin‐ and Muscarinic‐Evoked Release of [ 3 H]Noradrenaline from SH‐SY5Y Cells
Author(s) -
Purkiss John R.,
Nahorski Stefan R.,
Willars Gary B.
Publication year - 1995
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.1471-4159.1995.64031175.x
Subject(s) - thapsigargin , bradykinin , endocrinology , medicine , muscarinic agonist , muscarinic acetylcholine receptor , methacholine , chemistry , carbachol , inositol , intracellular , stimulation , biology , receptor , biochemistry , respiratory disease , lung
Abstract: The human neuroblastoma cell line SH‐SY5Y, maintained at confluence for 14 days, released [ 3 H]‐noradrenaline ([ 3 H]NA) when stimulated with either the muscarinic receptor agonist methacholine or bradykinin. The major fraction of release was rapid, occurring in <10 s, whereas nicotine‐evoked release was slower. When the extracellular [Ca 2+ ] ([Ca 2+ ] e ) was buffered to ∼50–100 n M , release evoked by nicotine was abolished, whereas that in response to methacholine or bradykinin was reduced by ∼50% with EC 50 values of −5.46 ± 0.05 M and −7.46 ± 0.06 M (log 10 ), respectively. Methacholine and bradykinin also produced rapid elevations of both inositol 1,4,5‐trisphosphate [Ins(1,4,5)P 3 ] and intracellular free [Ca 2+ ] ([Ca 2+ ] i ). These elevations were reduced at low [Ca 2+ ] e and under these conditions the EC 50 values for peak elevation of [Ca 2+ ] i were −6.00 ± 0.14 M for methacholine and −7.95 ± 0.34 M for bradykinin (n = 3 for all EC 50 determinations). At low [Ca 2+ ] e , depletion of nonmitochondrial intracellular Ca 2+ stores with the Ca 2+ ‐ATPase inhibitor thapsigargin produced a transient small elevation of [Ca 2+ ] i and a minor release of [ 3 H]NA. At low [Ca 2+ ] e , thapsigargin abolished elevation of [Ca 2+ ] i in response to methacholine and bradykinin and completely inhibited their stimulation of [ 3 H]NA release. It is proposed, therefore, that Ca 2+ release from Ins(1,4,5)P 3 ‐sensitive stores is a major trigger of methacholine‐ and bradykinin‐evoked [ 3 H]NA release in SH‐SY5Y cells.