The dependence of membrane potential on extracellular chloride concentration in mammalian skeletal muscle fibres.
The dependence of membrane potential on extracellular chloride concentration in mammalian skeletal muscle fibres.
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哺乳动物骨骼肌纤维中膜电位对细胞外氯化物浓度的依赖性。
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发表时间：
1978
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通讯作者：
A. Dulhunty
中科院分区：
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作者：
A. Dulhunty
1.用3 M-KCl玻璃微电极测量从小鼠趾长伸肌或比目鱼肌或大鼠胸锁乳突肌解剖的细束中纤维的稳态细胞内膜电位。研究发现稳态膜电位取决于细胞外Na、K和Cl离子的浓度。2.静息膜电位（3.5 mM-[K]o，160 mM-[Cl]o）为-74 +/-1 mV（平均值+/-S.E.）[Cl]o降低至3.5 mM导致可逆稳态超极化至-94 +/-1 mV（平均值+/-S.E.）。3.在暴露于不同[K]o和零[Cl]o的纤维中记录的稳态膜电位与Goldman，Hodgkin & Katz（GHK）方程预测的Na和K的电位一致。以Cl为主要外阴离子的类似实验结果不能用同一方程拟合。4.如果允许细胞内Cl浓度与稳态膜电位不平衡，则Na、K和Cl的GHK方程确实拟合了从含有不同[K]o的溶液中的纤维获得的数据，其中Cl是主要的外部阴离子。5.有人建议，一个积极的涌入Cl离子控制这些纤维中的细胞内Cl浓度，因此保持Cl平衡电位在去极化值相对于静息膜电位。6.大鼠膈肌纤维的稳态膜电位与[Cl]o无关，这些纤维的细胞内Cl浓度似乎不受主动Cl转运的控制。
1. The steady‐state intracellular membrane potential of fibres in thin bundles dissected from mouse extensor digitorum longus or soleus muscles or rat sternomastoid muscles was measured with 3 M‐KCl glass micro‐electrodes. The steady‐state membrane potential was found to depend on the extracellular concentrations of Na, K and Cl ions. 2. The resting membrane potential (3.5 mM‐[K]o, 160 mM‐[Cl]o) was ‐74 +/‐ 1 mV (mean +/‐ S.E.) and a reduction in [Cl]o to 3.5 mM caused a reversible steady‐state hyperpolarization to ‐94 +/‐ 1 mV (mean +/‐ S.E.). 3. The steady‐state membrane potentials recorded in fibres exposed to different [K]o and zero [Cl]o were consistent with potentials predicted by the Goldman, Hodgkin & Katz (GHK) equation for Na and K. The results of similar experiments done with Cl as the major external anion could not be fitted by the same equation. 4. The GHK equation for Na, K and Cl did fit data obtained from fibres in solutions containing different [K]o with Cl as the major external anion if the intracellular Cl concentration was allowed to be out of equilibrium with the steady‐state membrane potential. 5. It is suggested that an active influx of Cl ions controls the intracellular Cl concentrations in these fibres and hence maintains the Cl equilibrium potential at a depolarized value with respect to the resting membrane potential. 6. The steady‐state membrane potential of rat diaphragm fibres was independent of [Cl]o and it seems likely that the intracellular Cl concentration of these fibres is not controlled by active Cl transport.