title: Effects of cytochalasin B on the electrical activity of frog muscle fibers.
abstract: Cytochalasin B (50 mug/ml) markedly prolonged the falling phase of the action potential in frog sartorius muscle fibers without any effect on the rising phase and the amplitude of the action potential, nor on the resting potential. The maximum rate of fall of the action potential was reduced from 173 to 133 V/sec. The early depolarizing after-potential was increased in amplitude and lasted for as long as 1 sec. These changes in the falling phase of the action potential appear to be due to a slowing of sodium inactivation. Potassium conductance increase was not appreciably affected. The muscle treated with cytochalasin B responded to nerve stimulation with repetitive discharges which originated in presynaptic nerve elements.
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D003571:Cytochalasin B / Q000494:pharmacology*; D004553:Electric Conductivity; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects* / Q000502:physiology; D011188:Potassium / Q000502:physiology; D011894:Rana pipiens
chemical_list: D003571:Cytochalasin B; D011188:Potassium