Properties of caffeine- and potassium-contractures in fatigued frog single twitch muscle fibers.
Properties of caffeine- and potassium-contractures in fatigued frog single twitch muscle fibers.
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疲劳青蛙单抽动肌纤维中咖啡因和钾挛缩的特性。
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
T. Nagai
中科院分区：
文献类型：
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作者：
H. Kanaya;M. Takauji;T. Nagai
使用青蛙半腱肌（日本林蛙）详细检查了疲劳单纤维中咖啡因挛缩和钾挛缩的特性。疲劳是由 2 Hz 的重复刺激引起的。疲劳纤维中咖啡因挛缩的剂量反应曲线向右移动；正常纤维收缩的咖啡因阈浓度为 1.5 mM，而疲劳纤维收缩的阈浓度为 5 mM。然而，在存在 25 mM K+ 或 0.01% Triton X-100 的情况下，即使在疲劳纤维中，咖啡因收缩在较低浓度 (3-5 mM) 下也足以发生。此外，在疲劳纤维中，60或80 mM KC1（C1常数；120 mM）的双相钾挛缩的初始成分的峰值张力被轻微抑制，而挛缩的次要成分被显着抑制。这些结果表明，在疲劳纤维中，纤维的横向管状膜（T 膜）对咖啡因的渗透性以及响应于 K+ 对 T 膜直接去极化的 Ca 离子内流均受到显着抑制。
The properties of caffeine contracture and potassium contracture in fatigued single fibers were examined in detail using frog semitendinosus muscle, Rana japonica. Fatigue was caused by repetitive stimulation at 2 Hz. The dose-response curve of caffeine contracture in the fatigued fibers was shifted toward the right; the threshold concentration of caffeine for the contracture in normal fibers was 1.5 mM, whereas that in fatigued fibers was 5 mM. However, in the presence of 25 mM K+ or 0.01% Triton X-100, caffeine contractures occurred sufficiently at the lower concentrations (3-5 mM) even in the fatigued fibers. Furthermore, in the fatigued fibers, the peak tension of the initial component of biphasic potassium contracture with 60 or 80 mM KC1 (C1 constant; 120 mM) was slightly inhibited, whereas the secondary component of the contracture was markedly inhibited. These results indicate that the permeability to caffeine of the transverse tubular membrane (T-membrane) of the fibers and the Ca influx in response to the direct depolarization of T-membrane with K+ are markedly inhibited in the fatigued fibers.