Robinson H P, Sahara Y, Kawai N
Department of Neurobiology, Tokyo Metropolitan Institute for Neurosciences, Japan.
Biophys J. 1991 Feb;59(2):295-304. doi: 10.1016/S0006-3495(91)82223-8.
In order to measure unitary properties of receptor channels at the postsynaptic site, the noise within the decay phases of inhibitory postsynaptic currents (IPSCs) and of N-methyl-D-aspartate (NMDA)-dependent excitatory postsynaptic currents (EPSCs) in rat hippocampal neurons was studied by nonstationary fluctuation analysis. Least squares scaling of the mean current was used to circumvent the wide variation in amplitude of postsynaptic currents. The variance of fluctuations around the expected current was analyzed to calculate single channel conductance, and fluctuation kinetics were studied with power spectra. The single channel conductance underlying the IPSC was measured as 14 pS, whereas that underlying the EPSC was 42 pS. Openings of the EPSC channel could also be resolved directly in low-noise whole-cell recordings, allowing verification of the accuracy of the fluctuation analysis. The results are the first measurements of the properties of single postsynaptic channels activated during synaptic currents, and suggest that the technique can be widely applicable in investigations of synaptic mechanism and plasticity.
为了测量突触后位点受体通道的单一特性，通过非平稳波动分析研究了大鼠海马神经元中抑制性突触后电流（IPSCs）和N-甲基-D-天冬氨酸（NMDA）依赖性兴奋性突触后电流（EPSCs）衰减阶段的噪声。使用平均电流的最小二乘缩放来规避突触后电流幅度的广泛变化。分析预期电流周围波动的方差以计算单通道电导，并通过功率谱研究波动动力学。IPSC的单通道电导测量为14 pS，而EPSC的单通道电导为42 pS。EPSC通道的开放也可以在低噪声全细胞记录中直接分辨出来，从而验证波动分析的准确性。这些结果是对突触电流期间激活的单个突触后通道特性的首次测量，并表明该技术可广泛应用于突触机制和可塑性的研究。
