Finger W, Pareto A
Physiologisches Institut der Technischen Universität München, F.R.G.
Neurosci Lett. 1987 Sep 11;80(1):49-54. doi: 10.1016/0304-3940(87)90493-9.
Single channel currents were recorded by means of the patch-clamp technique from a tonic (slow) crayfish muscle in the presence of 5 mM glutamate. The experiments were carried out with 'Gigaohm-seals' in the 'cell-attached' mode at 15-17 degrees C. Five classes of single channel currents with different mean amplitudes were resolved: i1 = -0.75 +/- 0.43 (S.D.) pA, i2 = -1.4 +/- 0.4 pA, i3 = -3.5 +/- 0.63 pA, i4 = -8.5 +/- 0.92 pA and i5 approximately equal to 2 X i4, i2, i3 and i4 were recorded at resting membrane potential, Eo approximately equal to -80 mV (pipette potential Vp = 0), while i1 and i5 were recorded at 40 mV hyperpolarized to Eo (Vp = +40 mV). The current most frequently seen was i4 which is the excitatory glutamate-activated single channel current recorded previously by Franke et al. The membrane reversal potentials and channel conductances for i2 and i4 were estimated to be +60 mV (Eo + 140 mV), 13 pS for i2 and +40 mV (Eo + 120 mV), 80 pS for i4. It was assumed that up to 40 i1 currents could superpose in a single patch to generate a DC current of up to -30 pA with current fluctuations the intensity of which increased with the DC current amplitude. Often variable combinations of i1 to i4 currents could be recorded simultaneously in a single patch. In particular, simultaneous activity of i1, i4; i2, i4 and i3, i4 currents was observed in different single patches.
采用膜片钳技术，在5 mM谷氨酸存在的情况下，从一只强直性（慢速）小龙虾肌肉中记录单通道电流。实验在15 - 17摄氏度下以“千兆欧封接”的“细胞贴附”模式进行。分辨出了五类平均幅度不同的单通道电流：i1 = -0.75 ± 0.43（标准差）pA，i2 = -1.4 ± 0.4 pA，i3 = -3.5 ± 0.63 pA，i4 = -8.5 ± 0.92 pA且i5约等于2×i4，i2、i3和i4是在静息膜电位Eo约为 -80 mV（吸管电位Vp = 0）时记录的，而i1和i5是在比Eo超极化40 mV（Vp = +40 mV）时记录的。最常出现的电流是i4，它是先前由弗兰克等人记录的兴奋性谷氨酸激活的单通道电流。i2和i4的膜反转电位和通道电导估计分别为 +60 mV（Eo + 140 mV），i2为13 pS以及 +40 mV（Eo + 120 mV），i4为80 pS。据推测，单个膜片中最多可有40个i1电流叠加，以产生高达 -30 pA的直流电流，其电流波动强度随直流电流幅度增加。在单个膜片中常常能同时记录到i1至i4电流的不同组合。特别是，在不同的单个膜片中观察到了i1、i4；i2、i4和i3、i4电流的同时活动。
