Power-Law Behavior of Beat-Rate Variability in Monolayer Cultures of Neonatal Rat Ventricular Myocytes

Slow conduction and unidirectional conduction block (UCB) are key mechanisms of reentry. Following abrupt changes in heart rate, dynamic changes of conduction velocity (CV) and structurally determined UCB may critically influence arrhythmogenesis. Using patterned cultures of neonatal rat ventricular myocytes grown on microelectrode arrays, we investigated the dynamics of CV in linear strands and the behavior of UCB in tissue expansions following an abrupt decrease in pacing cycle length (CL). Ionic mechanisms underlying rate-dependent conduction changes were investigated using the Pandit-Clark-Giles-Demir model. In linear strands, CV gradually decreased upon a reduction of CL from 500 ms to 230-300 ms. In contrast, at very short CLs (110-220 ms), CV first decreased before increasing again. The simulations suggested that the initial conduction slowing resulted from gradually increasing action potential duration (APD), decreasing diastolic intervals, and increasing postrepolarization refractoriness, which impaired Na(+) current (I(Na)) recovery. Only at very short CLs did APD subsequently shorten again due to increasing Na(+)/K(+) pump current secondary to intracellular Na(+) accumulation, which caused recovery of CV. Across tissue expansions, the degree of UCB gradually increased at CLs of 250-390 ms, whereas at CLs of 180-240 ms, it first increased and subsequently decreased. In the simulations, reduction of inward currents caused by increasing intracellular Na(+) and Ca(2+) concentrations contributed to UCB progression, which was reversed by increasing Na(+)/K(+) pump activity. In conclusion, CV and UCB follow intricate dynamics upon an abrupt decrease in CL that are determined by the interplay among I(Na) recovery, postrepolarization refractoriness, APD changes, ion accumulation, and Na(+)/K(+) pump function.

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“…Activation times were defined at the occurrence of the minimum of the first derivative of the extracellular electrograms (30).…”

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confidence: 99%

Dynamic changes of cardiac conduction during rapid pacing

Kondratyev

Ponard²,

Munteanu³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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“…This is an important issue in all extracellular recordings since the electrophysiological signals have amplitudes from 100 V p-p to 1-2 mV p-p for rat cardiomyocytes (Kucera et al, 2000) and from 20 V p-p to 200 V p-p for vertebrate neurons. The maximum signal bandwidth is between 0 Hz and 4 kHz.…”

Section: Discussionmentioning

confidence: 99%

High-density electrode array for imaging in vitro electrophysiological activity

Berdondini

Wal

Guénat

et al. 2005

Biosensors and Bioelectronics

108

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The development of a high-density active microelectrode array for in vitro electrophysiology is reported. Based on the Active Pixel Sensor (APS) concept, the array integrates 4096 gold microelectrodes (electrode separation 20 m) on a surface of 2.5 mm × 2.5 mm as well as a high-speed random addressing logic allowing the sequential selection of the measuring pixels. Following the electrical characterization in a phosphate solution, the functional evaluation has been carried out by recording the spontaneous electrical activity of neonatal rat cardiomyocytes. Signals with amplitudes from 130 V p-p to 300 V p-p could be recorded from different pixels. The results demonstrate the suitability of the APS concept for developing a new generation of high-resolution extracellular recording devices for in vitro electrophysiology.

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“…The substrates consisted of glass plates (2121 mm, 0.7 mm thick) carrying up to 72 transparent ITO (indium-tin oxide) recording/stimulation electrodes [13]. The leads of the electrodes were insulated with a polymer layer (SU-8, 5 m thick).…”

Section: Multi-electrode Arraysmentioning

confidence: 99%

Photolithographically defined deposition of attachment factors as a versatile method for patterning the growth of different cell types in culture

Rohr

Flückiger-Labrada

Kučera

2003

Pflugers Arch - Eur J Physiol

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Spatially defined growth of cells in culture is a useful model for studies ranging from the characterization of cellular motility to the analysis of network behaviour in structurally defined ensembles of excitable cells. Current methodological approaches for obtaining patterned growth include sophisticated modifications of surface chemistry, stamping techniques and microfluidics. The implementation of most of these techniques requires the availability of highly specialized apparatus and some of the methods are specific for certain cell types and/or substrate materials. The goal of the present study was to develop a cell-patterning technique that can be implemented by any laboratory working with cell culture and that is highly adaptable in terms of cell types and substrate materials. The method is based on a photolithographic process that permits the patterned deposition of attachment factors of choice on surfaces previously coated with agar with a spatial resolution (maximal deviation from a straight line) of +/-3 micro m. Because agar efficiently prevents cell adhesion, patterned growth obtained with this technique displays virtually no off-pattern cell attachment. The method permitted the patterning of cardiomyocytes, fibroblasts and HeLa cells on either glass substrates or polymer-coated materials with a spatial resolution of a few micrometers.

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Power-Law Behavior of Beat-Rate Variability in Monolayer Cultures of Neonatal Rat Ventricular Myocytes

Cited by 56 publications

References 28 publications

Dynamic changes of cardiac conduction during rapid pacing

Dynamic changes of cardiac conduction during rapid pacing

High-density electrode array for imaging in vitro electrophysiological activity

Photolithographically defined deposition of attachment factors as a versatile method for patterning the growth of different cell types in culture

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