© 2000 American Heart Association, Inc.
Cellular Biology |
Power-Law Behavior of Beat-Rate Variability in Monolayer Cultures of Neonatal Rat Ventricular Myocytes
From the Department of Physiology (J.P.K., S.R.), University of Bern, and Institute of Microsystems (M.O.H., P.R.), Swiss Federal Institute of Technology, Lausanne, Switzerland.
Correspondence to Jan P. Kucera, MD, Physiologisches Institut, Bühlplatz 5, CH-3012 Bern, Switzerland. E-mail kucera{at}pyl.unibe.ch
Abstract—It is known that extracardiac factors (nervous, humoral, and hemodynamic) participate in the power-law behavior of heart-rate variability. To assess whether intrinsic properties of cardiac tissue might also be involved, beat-rate variability was studied in spontaneously beating cell cultures devoid of extracardiac influences. Extracellular electrograms were recorded from monolayer cultures of neonatal rat ventricular myocytes under stable incubating conditions for up to 9 hours. The beat-rate time series of these recordings were examined in terms of their Fourier spectra and their Hurst scaling exponents. A non-0 Hurst exponent was found in 21 of 22 preparations (0.29±0.09; range, 0.11 to 0.45), indicating the presence of fractal self-similarity in the beat-rate time series. The same preparations exhibited power-law behavior of the power spectra with a power-law exponent of -1.36±0.24 (range, -1.04 to -1.96) in the frequency range of 0.001 to 1 Hz. Furthermore, it was found that the power-law exponent was nonstationary over time. These results indicate that the power-law behavior of heart-rate variability is determined not only by extracardiac influences but also by components intrinsic to cardiac tissue. Furthermore, the presence of power-law behavior in monolayer cultures of cardiomyocytes suggests that beat-rate variability might be determined by the complex nonlinear dynamics of processes occurring at the level of the cellular network, eg, interactions among a large number of cell oscillators or metabolic regulatory systems.
Key Words: heart-rate variability • cardiac cell cultures • physiology • extracellular recording
This article has been cited by other articles:
 |
|
 |
|
  R. Lewandowski, K. Procida, R. Vaidyanathan, W. Coombs, J. Jalife, M. S. Nielsen, S. M. Taffet, and M. Delmar RXP-E: A Connexin43-Binding Peptide That Prevents Action Potential Propagation Block Circ. Res., August 29, 2008; 103(5): 519 - 526. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Munteanu, A. A. Kondratyev, and J. P. Kucera Analysis of Damped Oscillations during Reentry: A New Approach to Evaluate Cardiac Restitution Biophys. J., February 1, 2008; 94(3): 1094 - 1109. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Schmidt, J. Saworski, K. Werdan, and U. Muller-Werdan Decreased beating rate variability of spontaneously contracting cardiomyocytes after co-incubation with endotoxin Innate Immunity, December 1, 2007; 13(6): 339 - 342. [Abstract] [PDF]
|
|
|
|
 |
|
 J. P. Fahrenbach, R. Mejia-Alvarez, and K. Banach The relevance of non-excitable cells for cardiac pacemaker function J. Physiol., December 1, 2007; 585(2): 565 - 578. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. G. C. Ponard, A. A. Kondratyev, and J. P. Kucera Mechanisms of Intrinsic Beating Variability in Cardiac Cell Cultures and Model Pacemaker Networks Biophys. J., May 15, 2007; 92(10): 3734 - 3752. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. A. Kondratyev, J. G. C. Ponard, A. Munteanu, S. Rohr, and J. P. Kucera Dynamic changes of cardiac conduction during rapid pacing Am J Physiol Heart Circ Physiol, April 1, 2007; 292(4): H1796 - H1811. [Abstract] [Full Text] [PDF]
|
|