title: Effect of the blocked inactivation of sodium channels on intracellular and extracellular action potentials from isolated frog muscle fibres.
abstract: The intra- and extracellular action potentials of isolated frog muscle fibres, treated with ATX II for blocking sodium inactivation, are investigated. In concentrations of 0.1 to 0.5 X 10(-6) M, ATX II leads to a considerable change of the repolarization phase of the intracellular potential, with a tendency toward achieving a plateau-type potential. In addition to the intracellular action potentials, extracellular action potentials were also recorded from the same fibres. Immediately next to the fibre membrane and at a small radial distance the extracellular potentials did not manifest essential differences compared with recordings under normal physiological conditions. Conclusions are reached about the influence of the blocked Na-inactivation on the intra- and extracellular action potentials of muscle fibres.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003064:Cnidarian Venoms / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects*; D011895:Rana ridibunda; D011896:Rana temporaria; D012964:Sodium / Q000378:metabolism*
chemical_list: D003064:Cnidarian Venoms; D007473:Ion Channels; C028800:toxin II (Anemonia sulcata); D012964:Sodium