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Effects of sulphydryl inhibitors on frog sartorius muscle: p ‐chloromercuribenzoic acid and p ‐chloromercuribenzenesulphonic acid
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.tb10657.x
Subject(s) - sartorius muscle , chemistry , efflux , depolarization , biophysics , membrane potential , intracellular , biochemistry , biology
Summary1 . Experiments were done on frog sartorius muscles to study the effects and mechanisms of action of the –SH inhibitors, p ‐chloromercuribenzoic acid (PCMB) and p ‐chloromercuribenzenesulphonic acid (PCMBS). 2 . Both organomercurials produce a depolarization of the surface membrane which is associated with a period of asynchronous twitching and followed by inexcitability. 3 . Only PCMB produces a unique fractionation of the electrically evoked twitch into an initial rapid and later slow phase. 4 . PCMB and PCMBS increase the rate of 45 Ca efflux from whole muscle. Ethylenediamine tetraacetic acid (EDTA, 5 m m ) causes only limited antagonism of the enhancement of 45 Ca efflux produced by PCMB whereas it completely antagonizes this same effect of PCMBS. EDTA selectively removes superficial calcium without penetrating into the intracellular space. 5 . The results suggest that PCMB inhibits –SH groups in the terminal cisternae causing a fractionation of the twitch. PCMBS acts primarily at surface sites with limited access to the cisternae and sarcoplasmic reticulum.