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Effects of sulphydryl inhibitors on frog sartorius muscle: N‐ethylmaleimide
Author(s) -
KIRSTEN E. B.,
KUPERMAN† A. S.
Publication year - 1970
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1970.tb10658.x
Subject(s) - sartorius muscle , rigour , depolarization , calcium , endoplasmic reticulum , biophysics , chemistry , n ethylmaleimide , membrane potential , muscle contraction , endocrinology , medicine , biochemistry , biology , geometry , mathematics , organic chemistry
Summary1 . The characteristic action of the –SH inhibitor, N‐ethylmaleimide (NEM), is muscle rigour. The dose‐response curve indicates a biphasic effect with maximum rigour tension produced by 10 m m NEM; beyond 1.0 m m there was an inverse relationship between dose and response. 2 . NEM produces a membrane depolarization unrelated to rigour development. 3 . NEM causes a sustained increase in 45 Ca efflux from whole muscle. Pretreatment of a muscle with ethylenediamine tetra‐acetic acid (EDTA, 5 m m ) to remove membrane calcium does not alter the NEM induced 45 Ca efflux. 4 . It is suggested that the primary site of NEM action is inhibition of calcium uptake by the sarcoplasmic reticulum thereby producing rigour. At concentrations above 1.0 m m , NEM may affect the myofilaments.