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SODIUM CURRENTS IN SKELETAL MUSCLE FIBRES FROM THE TOAD BUFO MARINUS
Author(s) -
Arispe N. J.,
Argibay J. A.,
Rojas L. V.
Publication year - 1984
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1984.sp002837
Subject(s) - toad , bufo marinus , amphibian , sodium , sartorius muscle , biophysics , bufo , voltage clamp , electrophysiology , ionic bonding , chemistry , sodium fluoride , membrane potential , salientia , fluoride , anatomy , ion , biology , endocrinology , inorganic chemistry , biochemistry , ecology , xenopus , neuroscience , organic chemistry , gene
Single fibres from the sartorius muscle of the toad Bufo marinus were used to study ionic currents, using a fast voltage‐clamp method. Sodium currents were analysed following Hodgkin‐Huxley formulations. Internal caesium fluoride blocks delayed currents but produced shifts in the equilibrium potential of the early channel due to sodium accumulation. Delayed channels are very unstable when fluoride is used inside the fibre. These instabilities and equilibrium potential shifts were eliminated on replacing fluoride by aspartate in the internal solution. Late peaks of inward current, probably associated with activity at the tubular system, were occasionally observed for small depolarizations. The results are compared with those obtained for other amphibian species and used to explain more general electrophysiological properties of muscle fibres of this tropical toad.