Small clusters of ventricular cells prepared from 7-d chick heart maintain spontaneous, stationary, rhythmic beating in culture for many hours. For clusters containing I-125 cells, mean interbeat interval (IBI) is 0.45 +/- 0.08 s and is independent of cell number (N), whereas, the coefficient of variation of IBI (C) is proportional to N-1/2. Because membrane voltage noise in such clusters would also be expected to vary as N-1/2, we propose a model relating fluctuation in IBI (sigma IBI) to voltage noise (sigma v). A simplified model consisting of random voltage fluctuations superimposed upon a linear pacemaker depolarization of slope a is used to analyze the N-dependent shape of the IBI histogram. Values of sigma v derived from the relation sigma IBI = sigma v/a, or calculated from the skewness of the measured IBI histograms, both agree well with those extrapolated from steady-state noise recorded from resting heart-cell aggregates.
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机译:从7天鸡心制备的小室室细胞群在培养物中持续自发,平稳,有节奏地跳动许多小时。对于包含I-125电池的群集,平均心跳间隔(IBI)为0.45 +/- 0.08 s,并且与电池数目(N)无关,而IBI的变异系数(C)与N-1 / 2成比例。由于此类簇中的膜电压噪声也可能会发生N-1 / 2的变化,因此我们提出了将IBI的波动(σIBI)与电压噪声(σv)相关的模型。一个简化的模型由随机电压波动组成,叠加在斜率a的线性起搏器去极化上,用于分析IBI直方图的N依赖形状。从关系sigma IBI = sigma v / a得出的sigma v值,或者从测量的IBI直方图的偏斜度计算得出的sigma v值,都与从静息心脏细胞聚集体记录的稳态噪声推断出的值非常吻合。
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