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Dihydropyridine‐sensitive Ca 2+ channel in aneurally cultured human muscles Relationship between high‐affinity binding site and inhibition of calcium uptake
Author(s) -
Desnuelle Claude,
Askanas Valerie,
Engel W.King
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80649-5
Subject(s) - nitrendipine , dihydropyridine , depolarization , chemistry , binding site , calcium , biophysics , calcium channel , ryanodine receptor , voltage dependent calcium channel , receptor , stereochemistry , biochemistry , biology , organic chemistry
Dihydropyridine‐sensitive Ca 2+ channels and the relationship between binding of dihydropyridine derivatives and depolarization‐induced Ca 2+ uptake have been studied in aneurally cultured human muscle. Analysis of the equilibrium binding of the 1,4‐dihydropyridine derivative (+)‐PN200‐110 revealed a single high‐affinity binding site with a K d of 0.15±0.05 nM and a B max of 87±12 fmol/mg protein. Inhibition of (+)‐[ 3 H]PN200‐110 binding by nitrendipine revealed a K i of 0.8 nM for the nitrendipine‐receptor complex. Depolarization of cultured human muscle achieved by elevating the K + concentration increased the uptake 45 Ca 2+ which was inhibited by nitrendipine with an IC 50 of 1.1 nM. This study demonstrates that aneurally cultured human muscle has dihydropyridine‐sensitive voltage‐dependent Ca 2+ channels which are functional when the fibers are depolarized.