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KMID : 0578319950050010086
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Molecules and Cells
1995 Volume.5 No. 1 p.86 ~ p.92
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Identification of the M3 Muscarinic Receptor which is Coupled to Phospholipase C and adenylyy Cyclase in SK-N-BE(2)C Cells
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Suh Byung-Chang
Kim Kyong-Tai
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Abstract
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The muscarinic cholinergic receptor in human neuroblastoma SK-N-BE(2)C cells was identified and characterized by treatment with carbachol, the cholinergic receptor agonist. Carbachol (1 mM) increased the intracellular Ca^(2+) concentration ([Ca6(2+)_(i) and the inositol 1,4,5-trisphosphate level. The muscarinic receptor antagonists decreased the above carbachol-induced responses with a potency order of p-fluorohexahydrosiladifenidol (IC_(50) = 0.5-0.8 μM) > pirenzepine(IC_(50) = 5-9 μM ) > methoctramine (IC_(50) = 20-30 μM), which are selective to M₃, M₁, and M₂ receptors, respectively. Carbachol slightly elevated the cAMP level by ~ 1.5 times but enhanced the prostaglandin E₂-induced cAMP accumulation synergistically, which was then completely inhibited by the addition of 10 μM atropine, the muscarinic receptor inhibitor. Carbachol-induced enhancement of cAMP accumulation was also inhibited by the specific antagonists with a potency order of M₃ > M₁ > M₂ and the IC_(50) values were similar to the values of inhibition of [Ca^(2+)]_(i) rise and IP₃ generation. Phorbol 12-myristate 13-acetate pretreatment decreased both carbachol-induced [Ca^(2+)]_(i) rise and cAMP accumulation. These results indicate that the activation of phospholipase C and adenylyl cyclase mediated by M₃ muscarinic receptors is inhibited by protein kinase C stimulation.
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KEYWORD
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