• 主题
高级搜索  >
历史搜索 清空历史
首页> 美国卫生研究院文献>The Journal of Physiology >Current—voltage curve of sodium channels and concentration dependence of sodium permeability in frog skin
【2h】

Current—voltage curve of sodium channels and concentration dependence of sodium permeability in frog skin

机译：青蛙皮肤中钠通道的电流-电压曲线和钠渗透率的浓度依赖性

代理获取
本网站仅为用户提供外文OA文献查询和代理获取服务，本网站没有原文。下单后我们将采用程序或人工为您竭诚获取高质量的原文，但由于OA文献来源多样且变更频繁，仍可能出现获取不到、文献不完整或与标题不符等情况，如果获取不到我们将提供退款服务。请知悉。
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

1. The inward facing membranes of in vitro frog skin epithelium were depolarized with solutions of high K concentration. The electrical properties of the epithelium are then expected to be governed by the outward facing, Na-selective membrane.2. In this state, the transepithelial voltage (V) was clamped to zero and step-changes of Na activity in the outer solution ((Na)o) were performed with a fast-flow chamber at constant ionic strength, while the short-circuit current was recorded.3. At pre-selected times after a step-change of (Na)o the current response (I) to a fast voltage staircase was recorded. This procedure was repeated after blocking the Na channels with amiloride to obtain the current—voltage curve of transmembrane and paracellular shunt pathways. The current—voltage curve of the Na channels was computed by subtracting the shunt current from the total current.4. The instantaneous INa—V curve thus obtained at a given (Na)o could easily be fitted with the constant field equation in the range between -50 and zero mV. This fit yielded approximate estimates of PNa, the Na— permeability of the Na-selective membrane (at this (Na)o) and the cellular Na activity, (Na)c. As residual properties of the serosal membrane were ignored the computed values are expected to underestimate the true ones.5. At constant (Na)c, the steady-state value of 1/PNa increases linearly with (Na)o. Error analysis and the effect of drugs show that the dependence is not due to the residual properties of the inward facing membranes but reflects the true behaviour of PNa.6. The steady-state PNa at a given (Na)o is smaller than the transient PNa observed right after a stepwise increase of (Na)o to this value. The time constant of PNa-relaxation is in the order of seconds.7. In conclusion, Na transport through open Na-selective channels of the outward facing membrane of the stratum granulosum cells can be described as an electrodiffusion process which as such does not saturate with increasing (Na)o. However, when added to the outer border of the membrane Na causes a decrease of PNa within several seconds. It is considered that binding of Na results in closure of Na channels.
机译：1.用高K浓度溶液使体外蛙皮上皮的向内膜去极化。然后预期上皮的电特性将由面向外的Na选择性膜决定。2。在这种状态下，将上皮电压（V）钳制为零，并在恒定电流下用快速流动室在恒定离子强度下进行外部溶液（Na）o中Na活性的阶跃变化。被记录了3。在（Na）阶跃变化后的预选时间，记录了对快速电压阶梯的电流响应（I）。用阿米洛利阻断Na通道后重复此步骤，以获得跨膜和旁细胞分流途径的电流-电压曲线。通过从总电流中减去分流电流来计算Na通道的电流-电压曲线。4。因此，在给定的（Na）o下获得的瞬时INa-V曲线可以很容易地与-50和零mV之间的常数场方程拟合。该拟合得出PNa，Na选择性膜的Na-渗透性（在此（Na）o下）和细胞Na活性（Na）c的近似估计。由于忽略了浆膜的残留特性，预计计算值会低估真实值。5。在常数（Na）c下，1 / PNa的稳态值随（Na）o线性增加。误差分析和药物作用表明，依赖性不是由于内向膜的残留特性所致，而是反映了PNa.6的真实行为。给定（Na）o的稳态PNa小于（Na）o逐步增加到该值后立即观察到的瞬态PNa。 PNa松弛的时间常数约为秒7。总之，通过颗粒层细胞的面向外膜的开放Na选择通道的Na转运可以描述为电扩散过程，因此不会随着（Na） o 的增加而饱和。但是，当添加到膜的外边界时，Na会导致P Na 在几秒钟内减少。认为Na的结合导致Na通道的封闭。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
代理获取

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号