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Dihydropyridine [ methyl ‐ 3 H]PN 200–110 Binding and Myogenesis in Intact Muscle Cells In Vitro
Author(s) -
Navarro Javier
Publication year - 1986
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.1471-4159.1986.tb00632.x
Subject(s) - binding site , dissociation constant , dihydropyridine , myogenesis , calcium , chemistry , myocyte , intracellular , calcium in biology , in vitro , biophysics , receptor , biochemistry , microbiology and biotechnology , biology , organic chemistry
The radioligand dihydropyridine [ methyl ‐ 3 H]PN 200–110 binds to contracting myotubes in culture derived from chick embryo pectoralis muscle. [ methyl ‐ 3 H]PN 200–110 binds specifically to high‐affinity sites, with nonspecific binding only between 15 and 30% of the total binding. A Scatchard plot of the specific binding revealed a single high‐affinity binding site with a K D (dissociation constant) of 0.5 n M ± 0.2 n M and B max (number of binding sites) of 100 fmol/10 6 nuclei. We employed this sensitive assay to probe the appearance of high‐affinity [ methyl ‐ 3 H]PN 200–110 binding sites during myogenesis. The time course of appearance of high‐affinity binding sites lags behind that of fusion. Low‐calcium media prevented the differentiation of myoblasts and blocked the appearance of high‐affinity sites. Chelation of intracellular calcium before or after fusion of myoblasts with the calcium indicator Quin 2 prevented the appearance of dihydropyridine binding sites. These findings are consistent with the view that the expression of dihydropyridine receptors is modulated by the intracellular calcium.