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Effect of Some Calcium Antagonists on Muscarinic Receptor‐Mediated Cyclic GMP Formation
Author(s) -
ElFakahany Esam,
Richelson Elliott
Publication year - 1983
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.1471-4159.1983.tb08036.x
Subject(s) - verapamil , calcium , muscarinic acetylcholine receptor , quinuclidinyl benzilate , chemistry , endocrinology , medicine , extracellular , receptor , muscarinic acetylcholine receptor m1 , acetylcholine , pharmacology , biology , biochemistry
Several calcium antagonists were screened for their effect on muscarinic acetylcholine receptor‐mediated cyclic GMP formation in murine neuroblastoma cells (clone N1E‐115). Mn 2+ , Ni 2+ , and verapamil rapidly antagonized the response noncompetitively, with the following order of potency: verapamil > Mn 2+ > Ni 2+ . The effects of Mn 2+ and Ni 2+ , but not those of verapamil, were largely reversed by increasing extracellular calcium concentration. Additional effects of these agents included displacement of [ 3 H]quinuclidinyl benzilate binding by verapamil and elevation of cyclic GMP levels by Mn 2+ and Ni 2+ in the absence of agonists. These results are in support of the hypothesis that receptor‐mediated cyclic GMP formation by these cells is dependent upon entry of calcium into the cell and demonstrate the complexity of the effects of calcium antagonists.