Chen P, Gillis K D
Department of Electrical Engineering, University of Missouri-Columbia, Research Park, Columbia, Missouri 65211, USA.
Biophys J. 2000 Oct;79(4):2162-70. doi: 10.1016/S0006-3495(00)76464-2.
High-resolution measurement of membrane capacitance in the whole-cell-recording configuration can be used to detect small changes in membrane surface area that accompany exocytosis and endocytosis. We have investigated the noise of membrane capacitance measurements to determine the fundamental limits of resolution in actual cells in the whole-cell mode. Two previously overlooked sources of noise are particularly evident at low frequencies. The first noise source is accompanied by a correlation between capacitance estimates, whereas the second noise source is due to "1/f-like" current noise. An analytic expression that summarizes the noise from thermal and 1/f sources is derived, which agrees with experimental measurements from actual cells over a large frequency range. Our results demonstrate that the optimal frequencies for capacitance measurements are higher than previously believed. Finally, we demonstrate that the capacitance noise at high frequencies can be reduced by compensating for the voltage drop of the sine wave across the series resistance.
在全细胞记录模式下对膜电容进行高分辨率测量，可用于检测伴随胞吐作用和胞吞作用的膜表面积的微小变化。我们研究了膜电容测量的噪声，以确定全细胞模式下实际细胞中分辨率的基本极限。在低频时，两个先前被忽视的噪声源尤为明显。第一个噪声源伴随着电容估计值之间的相关性，而第二个噪声源则是由于“类1/f”电流噪声。推导了一个总结热噪声和1/f噪声源的解析表达式，该表达式在很宽的频率范围内与实际细胞的实验测量结果一致。我们的结果表明，电容测量的最佳频率比先前认为的要高。最后，我们证明通过补偿正弦波在串联电阻上的电压降，可以降低高频时的电容噪声。
