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Muscarinic receptors coupled to phosphoinositide hydrolysis and elevated cytosolic calcium in a human neuroblastoma cell line SK‐N‐SH
Author(s) -
Baird John G.,
Lambert David G.,
McBain Julie,
Nahorski Stefan 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.tb12681.x
Subject(s) - inositol , inositol phosphate , carbachol , phospholipase c , muscarinic acetylcholine receptor , inositol trisphosphate , calcium in biology , intracellular , inositol trisphosphate receptor , gq alpha subunit , calcium , endocrinology , chemistry , fura 2 , biology , receptor , medicine , biochemistry , cytosol , g protein , organic chemistry , enzyme
1 The effects of the muscarinic agonist carbachol on phosphoinositide metabolism and its relationship to alteration of intracellular calcium were examined in SK‐N‐SH human neuroblastoma cells. Muscarinic receptors on these cells are coupled to phospholipase C and the myo [2‐ 3 H]‐inositol phosphates resulting from receptor activation of cells labelled with [ 3 H]‐inositol accumulate rapidly. The breakdown of both inositol monophosphate (InsP 1 ) and inositol bisphosphate (InsP 2 ) is sensitive to lithium with inhibition of the latter only observed at higher concentrations of this ion. 2 Use of the calcium indicator dye Fura 2 revealed that carbachol stimulates a biphasic increase in intracellular calcium. 3 Carbachol was able to stimulate both [ 3 H]‐inositol phosphate production and intracellular calcium levels with respective EC 50 values of 15.9 ± 1.0 μ m and 10.7 ± 3.2 μ m , indicating that no amplification occurs between these steps in the signal transduction pathway. 4 Inositol 1,4,5 trisphosphate (Ins(1,4,5)P 3 ) released 45 Ca 2+ in a stereospecific and dose‐related manner from intracellular stores of permeabilised cells. 5 These results suggest that this cell line may represent a useful model system to investigate receptor‐mediated phosphoinositide metabolism and calcium homeostasis.