Bossu J L, De Waard M, Fagni L, Tanzi F, Feltz A
Laboratoire de Neurobiologie Cellulaire, CNRS, associé à l'Université Louis Pasteur, Strasbourg, France.
Eur J Neurosci. 1994 Mar 1;6(3):335-44. doi: 10.1111/j.1460-9568.1994.tb00276.x.
The properties and characteristics of calcium channel openings in cerebellar granule cells were analysed by the cell-attached patch-clamp technique. At depolarized potentials, with 110 mM Ba2+ as the divalent charge carrier, 36% of the patches displayed activity that consisted of elementary events whose amplitude ranged from -0.3 to -1.75 pA at 0 mV, giving rise to a high threshold current. In this population of events at least four different types of channel openings were identified by their distinct biophysical and pharmacological properties. Two types of channel openings, with conductances around 24 and 7 pS, had similar characteristics in that both opened following two modes of gating characterized by brief (approximately 2 ms) and longer openings (approximately 8 ms) and both were sensitive to dihydropyridines. A further type of channel opening, with a conductance around 11 pS gated mainly with brief openings (approximately 1 ms), was shown to be insensitive to dihydropyridines but was undetectable in recordings from the cells that had been treated with omega-conotoxin. The last type of event was revealed after treatment of the cell with nicardipine or nifedipine and omega-conotoxin. The corresponding channel had a conductance of 19 pS and opened in one dominant mode characterized by brief openings (approximately 1 ms). The data obtained on single-channel activity of cerebellar granule cells are compared with the properties of the total current recorded in whole-cell conditions.
采用细胞贴附式膜片钳技术分析了小脑颗粒细胞中钙通道开放的特性。在去极化电位下，以110 mM Ba2+作为二价电荷载体时，36%的膜片表现出由基本事件组成的活性，这些基本事件在0 mV时的幅度范围为-0.3至-1.75 pA，产生高阈值电流。在这群事件中，至少有四种不同类型的通道开放通过其独特的生物物理和药理学特性得以识别。两种通道开放类型，电导分别约为24和7 pS，具有相似的特征，即两者都通过两种门控模式开放，其特征分别为短暂（约2 ms）和较长时间（约8 ms）的开放，并且两者都对二氢吡啶敏感。另一种通道开放类型，电导约为11 pS，主要通过短暂开放（约1 ms）门控，显示对二氢吡啶不敏感，但在用ω-芋螺毒素处理的细胞记录中无法检测到。最后一种事件类型是在用尼卡地平或硝苯地平和ω-芋螺毒素处理细胞后发现的。相应的通道电导为19 pS，并以一种以短暂开放（约1 ms）为特征的主导模式开放。将小脑颗粒细胞单通道活性获得的数据与全细胞条件下记录的总电流特性进行了比较。
