非兴奋性组织细胞膜中电压依赖性电导的特性：两栖类晶状体。

Characteristics of voltage-dependent conductance in the membranes of a non-excitable tissue: the amphibian lens.

作者信息

Delamere N A, Duncan G, Paterson C A

出版信息

J Physiol. 1980 Nov;308:49-59. doi: 10.1113/jphysiol.1980.sp013461.

DOI:10.1113/jphysiol.1980.sp013461

PMID:6971930

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1274538/

Abstract

The electrical conductance of the frog lens membranes was observed to increase when the lens was depolarized by current, and to decrease when the lens was hyperpolarized. 2. The total lens conductance (GT) could be described by a voltage-dependent component (GH) together with a voltage-insensitive component (GO). 3. Conductance measured at the resting potential increased from 9.7 to 14.4 x 10(-5) S when the lens was depolarized by 9.1 mV in 10(-4) M-ouabain. The increase of conductance could be explained by an increase of GH which resulted from the depolarization alone. 4. Potassium-rich solutions influenced the conductance by increasing GH as the result of depolarization and by decreasing (blocking) GO. Small increases in the external potassium concentration (from 2.5 to 5 mM), which did not depolarize the lens, resulted in a decrease in resting conductance due to the blockade of GO. 5. Conductance-voltage relationships established in 2.5 (control), 5, 12.5 and 25 mM external potassium could each be fitted to a single mathematical model by assuming that GO had been reduced for 5.0 (control) to 4.5, 3 and 1 x 10(-5) S respectively by those increased potassium concentrations. 6. Barium (2 mM) depolarized the lens by 14.3 mV and decreased the resting conductance by 39%. When the lens was depolarized by a step current pulse in the presence of barium, the conductance increased with time after the onset of the current. Hyperpolarization elicited less time dependence of the conductance. 7. Barium reduced the extent to which lens conductance was dependent on voltage.

摘要

当通过电流使蛙晶状体膜去极化时，观察到其电导增加；当晶状体超极化时，电导则降低。2. 晶状体的总电导（GT）可由一个电压依赖性成分（GH）和一个电压不敏感成分（GO）共同描述。3. 在10⁻⁴ M哇巴因中，当晶状体被去极化9.1 mV时，静息电位下测得的电导从9.7×10⁻⁵ S增加到14.4×10⁻⁵ S。电导的增加可通过仅由去极化导致的GH增加来解释。4. 富含钾的溶液通过去极化增加GH以及通过降低（阻断）GO来影响电导。外部钾浓度的小幅增加（从2.5 mM增加到5 mM），这并未使晶状体去极化，却因GO的阻断导致静息电导降低。5. 通过假设那些增加的钾浓度已将GO分别从5.0（对照）降低到4.5、3和1×10⁻⁵ S，在2.5（对照）、5、12.5和25 mM外部钾中建立的电导 - 电压关系均可拟合到一个单一的数学模型。6. 钡（2 mM）使晶状体去极化14.3 mV，并使静息电导降低39%。当在钡存在的情况下通过阶跃电流脉冲使晶状体去极化时，电导在电流开始后随时间增加。超极化引起的电导时间依赖性较小。7. 钡降低了晶状体电导对电压的依赖程度。