Magistretti J, Mantegazza M, de Curtis M, Wanke E
Laboratorio di Neurofisiologia Sperimentale, Istituto Nazionale Neurologico Carlo Besta, Milan, Italy.
Biophys J. 1998 Feb;74(2 Pt 1):831-42. doi: 10.1016/S0006-3495(98)74007-X.
An extensive evaluation of the possible alterations affecting physiological voltage signals recorded with patch-clamp amplifiers (PCAs) working in the current-clamp (CC) mode was carried out by following a modeling approach. The PCA output voltage and current signals obtained during CC recordings performed under simplified experimental conditions were exploited to determine the equations describing the generation of error currents and voltage distortions by PCAs. The functions thus obtained were used to construct models of PCAs working in the CC mode, which were coupled to numerical simulations of neuronal bioelectrical behavior; this allowed us to evaluate the effects of the same PCAs on different physiological membrane-voltage events. The models revealed that rapid signals such as fast action potentials are preferentially affected, whereas slower events, such as low-threshold spikes, are less altered. Prominent effects of model PCAs on fast action potentials were alterations of their amplitude, duration, depolarization and repolarization speeds, and, most notably, the generation of spurious afterhyperpolarizations. Processes like regular firing and burst firing could also be altered, under particular conditions, by the model PCAs. When a cell consisting of more than one single intracellular compartment was considered, the model PCAs distorted fast equalization transients. Furthermore, the effects of different experimental and cellular parameters (series resistance, cell capacitance, temperature) on PCA-generated artifacts were analyzed. Finally, the simulations indicated that no off-line correction based on manipulations of the error-current signals returned by the PCAs can be successfully performed in the attempt to recover unperturbed voltage signals, because of alterations of the overall current flowing through the cell-PCA system.
通过建模方法，对在电流钳（CC）模式下工作的膜片钳放大器（PCA）记录的生理电压信号可能受到的改变进行了广泛评估。利用在简化实验条件下进行CC记录时获得的PCA输出电压和电流信号，来确定描述PCA产生误差电流和电压失真的方程。由此得到的函数用于构建在CC模式下工作的PCA模型，并将其与神经元生物电行为的数值模拟相结合；这使我们能够评估相同PCA对不同生理膜电压事件的影响。模型显示，快速信号如快速动作电位受到的影响更为显著，而较慢的事件如低阈值尖峰则受影响较小。模型PCA对快速动作电位的显著影响包括其幅度、持续时间、去极化和复极化速度的改变，最值得注意的是，会产生虚假的超极化后电位。在特定条件下，模型PCA也可能改变如规则发放和爆发性发放等过程。当考虑由多个单个细胞内区室组成的细胞时，模型PCA会扭曲快速平衡瞬变。此外，还分析了不同实验和细胞参数（串联电阻、细胞电容、温度）对PCA产生伪迹的影响。最后，模拟结果表明，由于流经细胞-PCA系统的总电流发生了改变，试图通过对PCA返回的误差电流信号进行操作来进行离线校正，以恢复未受干扰的电压信号是无法成功实现的。
