亚甲蓝和抗坏血酸盐对青蛙骨骼肌跨膜电位的影响。

Effects of methylene blue and ascorbate on transmembrane potential in frog skeletal muscle.

作者信息

Nánási P P, Dely M

机构信息

Department of Physiology, University Medical School of Debrecen, Hungary.

出版信息

Gen Pharmacol. 1995 Oct;26(6):1307-11. doi: 10.1016/0306-3623(95)00007-n.

DOI:10.1016/0306-3623(95)00007-n

Abstract

The effects of methylene blue (MB, 10(-4) M) and ascorbate (ASC, 10(-4) M) on the resting membrane potential of frog skeletal muscle fibers were studied in Cl(-)-free medium at various external K+ concentrations. 2. Muscle fibers formed two distinct populations according to their resting potentials (hyperpolarized to -104 mV or depolarized to -31 mV) after a 90 min period of K+ withdrawal. ASC increased the relative contribution of hyperpolarized fibers, while in the presence of MB, all fibers depolarized during the 90 min of K+ withdrawal. 3. In the presence of 2.5 mM K+, ASC had no significant effect on the resting potential, while MB moved half of the fibers into the depolarized pool. Elevation of [K+]0 to 10 mM caused repolarization of all previously depolarized fibers (to -63 mV) in spite of the continuous presence of MB. 4. Ionic currents were measured during a 60 mV depolarization step using the double sucrose-gap technique. MB significantly increased the peak inward current, while ASC had no effect. The steady-state outward current was not affected by MB or ASC. 5. The results suggest that ionic conductances may be under redox control in frog skeletal muscle.

摘要

在无氯培养基中，于不同的外部钾离子浓度下，研究了亚甲蓝（MB，10⁻⁴ M）和抗坏血酸盐（ASC，10⁻⁴ M）对青蛙骨骼肌纤维静息膜电位的影响。2. 在钾离子去除90分钟后，肌肉纤维根据其静息电位形成了两个不同的群体（超极化至 -104 mV或去极化至 -31 mV）。ASC增加了超极化纤维的相对比例，而在MB存在的情况下，所有纤维在钾离子去除的90分钟内都发生了去极化。3. 在2.5 mM钾离子存在的情况下，ASC对静息电位没有显著影响，而MB使一半的纤维进入去极化池。尽管MB持续存在，但将[K⁺]₀提高到10 mM会使所有先前去极化的纤维复极化（至 -63 mV）。4. 使用双蔗糖间隙技术在60 mV去极化步骤期间测量离子电流。MB显著增加了内向电流峰值，而ASC没有影响。稳态外向电流不受MB或ASC的影响。5. 结果表明，青蛙骨骼肌中的离子电导可能受氧化还原控制。