HYPERPOLARIZATION OF FROG SKELETAL MUSCLE FIBRES INDUCED BY REMOVING POTASSIUM FROM BATHING MEDIUM
HYPERPOLARIZATION OF FROG SKELETAL MUSCLE FIBRES INDUCED BY REMOVING POTASSIUM FROM BATHING MEDIUM
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DOI：
10.1113/jphysiol.1971.sp009558
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发表时间：
1971-01-01
影响因子：
5.5
通讯作者：
GRUNDFEST, H
中科院分区：
文献类型：
--
作者：
AKIYAMA, T;GRUNDFEST, H
1.研究了24根青蛙单纤维和136根小束(2~4根)半腱肌标本去K0后静息电位变化的时间过程。对照生理盐水的初始静息电位范围为−88~−98 mV。在实验3-8小时后，当恢复控制条件时，电位几乎恢复到初始值。实验结束时，所有的纤维都抽动了。只有大约三分之一的纤维在室温(20-28°C)下暴露于无钾生理盐水中后，在任何时间内都超极化。在可变延迟后，超极化被逆转为去极化。静息电位可能降至−50或−40 mV.4。其余的纤维在很少或没有超极化的情况下去极化。这两种反应模式都可以在不同的纤维中复制。无钾溶液引起的超极化在降温至10℃、用Tris或Li替代Na以及用DNP(0.025-0.2 mM)或哇巴因(0.05 mM)抑制Na泵时被减弱或消除。后一种药剂不像其他条件那样有效。当用Tris或Li.8取代Na时，只发生了很小的、缓慢发展的去极化。在无钾溶液中的各种效应在返回到对照条件时被逆转。结果表明，K0的去除对静息电位的直接影响很小或没有直接影响，初始超极化是由于泵送的Na外流而没有K的补偿内流。随着K1的耗尽和Na1的增加，泵的生电受阻表现为纤维的去极化。钠泵似乎依赖于青蛙的营养状况，后者的变化可能导致纤维对去除K0的不同反应。
1. The time course of changes in resting potential after removing K0was studied in twenty‐four single fibres and in 136 fibres from small bundle (two to four fibres) preparations of frog semitendinosus muscles.2. The initial resting potentials in the control saline ranged between −88 and −98 mV. The potentials returned to nearly the initial values when control conditions were reinstated after 3‐8 hr of experimentation. All the fibres twitched at the end of the experiment.3. Only about one third of the fibres hyperpolarized for any length of time on exposure to a K‐free saline at room temperature (20–28° C). The hyperpolarization was reversed to depolarization after a variable delay. The resting potential could fall to −50 or −40 mV.4. The remainder of the fibres depolarized with little or no prior hyperpolarization.5. Both patterns of response could be replicated in the different fibres.6. Hyperpolarization induced by K‐free solution was reduced or abolished on cooling toca10°C; on substitution of Tris or Li for Na; and upon inhibition of the Na pump with DNP (0·025–0·2 mM) or ouabain (0·05 mM). The latter agent was not as effective as the other conditions.7. Only small, slowly developing depolarization occurred when Na was replaced with Tris or Li.8. The various effects in K‐free solutions were reversed on returning to the control conditions.9. It is suggested that removal of K0itself has little or no direct effect on the resting potential and that the initial hyperpolarization is due to the pumped efflux of Na without a compensatory influx of K. Block of the pump electrogenesis is manifested by depolarization of the fibres as K1is depleted and Na1increased.10. The Na pump appears to be dependent upon the nutritional status of the frogs and variations of the latter probably cause the different responses of fibres to removal of K0.