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Myasthenia gravis sera containing antiryanodine receptor antibodies inhibit binding of [ 3 H]‐ryanodine to sacroplasmic reticulum
Author(s) -
Skeie Geir Olve,
Lunde Per Kristian,
Sejersted Ole M.,
Mygland Åse,
Aarli Johan A.,
Gilhus Nils Erik
Publication year - 1998
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(199803)21:3<329::aid-mus6>3.0.co;2-c
Subject(s) - ryanodine receptor , myasthenia gravis , thymoma , antibody , endoplasmic reticulum , chemistry , calcium , acetylcholine receptor , endocrinology , medicine , skeletal muscle , receptor , biochemistry , biology , immunology
Myasthenia gravis (MG) patients with thymoma often have antibodies against the calcium‐release channel of the sarcoplasmic reticulum (SR) in striated muscle, the ryanodine receptor (RyR). RyR function can be tested in vitro by measuring the degree of [ 3 H]‐ryanodine binding to SR. In this study, sera from 9 out of 14 MG patients containing RyR antibodies inhibited [ 3 H]‐ryanodine binding to SR membranes from rat skeletal muscle. The 9 patients with antibodies inhibiting ryanodine binding had more severe MG than those with noninhibiting antibodies ( P = 0.006). Sera from MG patients with acetylcholine receptor and titin muscle antibodies but no antibodies against RyR and blood‐donor sera did not have an inhibiting effect in the [ 3 H]‐ryanodine binding assay. The results show that RyR antibodies in MG patients have high affinity for the RyR, and that the binding of antibodies probably affects calcium release from SR by locking the RyR ion channel in a closed position. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:329–335.