Haruka KAWATA

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1. Single skeletal muscle fibers were transferred from a normal Ringer solution to Na+ ion free solution, and vice versa, and tetanus responses were recorded immediately after the transfer. 2. Fractional tetanus tension recorded immediately after the displacement from the Na+ ion free solution to normal Ringer solution was dependent on fiber diameter. 3.(More)
Effects of Ba2+ ions on the contractility were investigated in the frog skeletal muscle under the current clamp condition. The membrane potential was depolarized by 10 to 20 mV by perfusing 2 mM Ba2+ for 5 to 10 min. Membrane resistance was first increased and then decreased. The mechanical threshold examined in TTX-containing solution was shifted to more(More)
Leptin has been recognized to be an important neuroendocrine signal in the regulation of food intake and energy balance. We aimed to survey central neurons that might be activated after peripheral administration of leptin, by examining the distribution of neurons expressing c-Fos protein. Leptin dissolved at a dose of 500 g/kg in physiological saline was(More)
Post-tetanic potentiation (PTP) was mimicked by post-contracture potentiation (PCP) in the twitch muscle of frog. A marked PCP was observed in small bundles of semitendinosus muscle in tetrodotoxin (TTX)-containing solution under current clamp condition. Contractures were induced by a constant depolarizing current pulse of 1 s every 5 min. Each contracture(More)
In order to investigate the mechanism by which elevated extracellular Ca ions decrease twitch and tetanus tension in frog skeletal muscle we made mechanical and electrophysiological measurements on single fibers or small bundles from twitch muscles. High concentration of Ca caused a hyperpolarization and an increase in the duration of action potential. The(More)
The effects of low Na on the tetanic contractility after trains of twitch were investigated in frog skeletal muscle. Tetanic tension was induced by a stimulation of 100 Hz for 400 msec every 5 min and a train of twitches (150 or 250) with 1 Hz was interposed between two successive tetani. When the Na concentration was reduced to 50% by replacement with(More)
  • H Kawata
  • 1983
The effects of twitch trains on the contractility of succeeding tetani were investigated in the frog toe muscle. The changes in isometric tension and its first derivative were analyzed. Tetani of 1 sec duration were induced every 5 min and trains of twitches (less than 250) with 0.1 to 3 Hz were interposed between two successive tetani. A twitch train which(More)
  • H Kawata
  • 1979
The effects of Na-free Li solution on the electrical and mechanical activities were examined in a bullfrog's ventricular strip. The action potential showed a triphasic change during Na-free perfusion: the initial decrease in the overshoot and duration, the secondary restoration and the gradual decrease in the membrane potential. The twitch contraction also(More)
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