Fluctuations in interbeat interval in rhythmic heart-cell clusters. Role of membrane voltage noise

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 var...

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Bibliographic Details
Published in:Biophysical journal 1979-12, Vol.28 (3), p.377-389
Main Authors: Clay, J.R., DeHaan, R.L.
Format: Article
Language:English
Subjects:
Animals
Cell Membrane - physiology
Cells, Cultured
Chick Embryo
Electrophysiology
Heart - physiology
Heart Rate
Models, Biological
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Summary: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.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(79)85187-5