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Inhibition of dihydropyridine‐sensitive calcium channels by the plant alkaloid ryanodine
Author(s) -
Valdivia Hector H.,
Coronado Roberto
Publication year - 1989
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(89)80557-5
Subject(s) - ryanodine receptor , dihydropyridine , chemistry , endoplasmic reticulum , calcium , voltage dependent calcium channel , alkaloid , biophysics , skeletal muscle , endocrinology , biochemistry , stereochemistry , biology , organic chemistry
At micromolar concentrations, ryanodine interacts with the dihydropyridine receptor of rabbit skeletal muscle transverse tubules. Ryanodine displaces specifically bound [ 3 H]PN200‐110 with an apparent inhibition constant of approx. 95 μM and inhibits dihydropyridine‐sensitive calcium channels in the same preparation with an IC 50 of approx. 45 μM. These concentrations of ryanodine are approximately three orders of magnitude higher than those required to saturate binding of the alkaloid to the ryanodine receptor of sarcoplasmic reticulum and to open the calcium release channel of sarcoplasmic reticulum (i.e. 20 nM (1988) J. Gen. Physiol. 92, 1–26). Thus at sufficiently high dose, ryanodine may affect SR as well as plasma membrane Ca permeabilities.