Osipenko O N, Kiss T
Department of General Physiology of Nervous System, A.A. Bogomoletz Institute of Physiology, Academy of Sciences of the Ukrainian S.S.R.
Acta Biochim Biophys Hung. 1991;26(1-4):39-49.
Patch-clamp technique was used in order to study properties of the steady-state Na-channel in snail neurons. Experiments revealed that Pb-ions, applied extracellularly, close these channels, which are preferably in open state at the resting membrane potential. Elementary currents have a linear current-voltage (I-V) relationship with single channel conductance of 14 pS between -100 and -40 mV both in control saline and in the presence of 50 microM Pb in the pipette. Pb-ions decreased the mean open and increased the mean closed time. It was found that both open and closed times showed little voltage-dependence, however the probabilities of the open and closed times proved to be voltage-dependent. Open and closed time histograms were fitted by one exponential, therefore first order kinetics were assumed for the blocking effect of Pb2+ at the single channel level.
为了研究蜗牛神经元中稳态钠通道的特性，采用了膜片钳技术。实验表明，细胞外施加的铅离子会关闭这些通道，这些通道在静息膜电位时更倾向于处于开放状态。在对照盐溶液和移液管中有50微摩尔铅存在的情况下，基本电流在-100至-40毫伏之间具有线性电流-电压（I-V）关系，单通道电导为14皮安。铅离子减少了平均开放时间并增加了平均关闭时间。研究发现，开放和关闭时间对电压的依赖性都很小，然而开放和关闭时间的概率被证明是电压依赖性的。开放和关闭时间直方图由一个指数拟合，因此假设在单通道水平上铅离子的阻断作用符合一级动力学。
