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Sodium currents in mammalian muscle
Author(s) -
Adrian R. H.,
Marshall M. W.
Publication year - 1977
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1977.sp011855
Subject(s) - sodium , chemistry , biophysics , microbiology and biotechnology , anatomy , biology , organic chemistry
1. A method is described which allows the approximate computation of membrane current from measurements with three electrodes in the mid‐region of a muscle fibre. 2. Measurements of inward sodium current in frog muscle are compared with the results of previous clamping studies to test the validity of the new method. 3. Sodium current in rat muscle (extensor digitorum longus) is in general similar to sodium current in frog muscle. Two differences in detail have been found between sodium current in rat and frog muscle: ( a ) at the same temperature (in the range 0‐20° C) inactivation is slower in the rat than in the frog; ( b ) in rat the steady‐state activation is shifted negatively on the voltage axis by some 10‐15 mV. 4. Delayed outward current and charge movement (Schneider & Chandler, 1973) are present in rat muscle. 5. Rat muscle fibres are more resistant than frog muscle fibres to the action of tetrodotoxin. Inward current is still detectable in rat muscle at 100 n M tetrodotoxin. We found no evidence to suggest the existence in rat muscle of two kinds of sodium channel, one sensitive and one less sensitive to tetrodotoxin.