Characterisation of re-entrant circuit (or rotational activity) in vitro using the HL1-6 myocyte cell line

Figures

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  Fig. 1. Proportion of colonies with observed re-entry wavefronts for different colony areas. Number of recordings for each area are indicated. *p < .05.

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  Fig. 2. (a) Number of natural triggers at each colony size for HL1-6, with significance levels indicated (b) Total number of wavefronts in 30 second recording at each colony size. Significance levels using the Mann-Whitney U test with Dunn's correction are indicated. Error bars are standard error to the mean. *p < .05, **p < .01.

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  Fig. 3. Activation map of a natural trigger at the edge of a colony. (a) fluo4-AM stained cells, (b) activation map and (c) activation map after depolarization with KCl and reactivation in normal medium. Both maps are virtually identical.

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  Fig. 4. Examples of re-entry core shapes and sizes. Dark areas correspond to large conduction delay between each side of the area. Scale bars are different between images because the frequency of re-entry was different.

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  Fig. 5. (a) Activation map of re-entry circuit in HL1-6, dominant frequency = 2.9 ± 0.1 Hz (b) Visualisation of re-entry core from a composed of multiple connected lines (c) Visualisation of re-entry core from a with calculated perimeter marked.

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  Fig. 6. Scatter plot showing perimeter of re-entry circuit core vs dominant frequency of re-entry. Linear regression line, p = .044, R2 = 0.15.

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  Fig. 7. (a) Conduction block visualisation of re-entry in HL1-6 with dominant frequency of 2.9 ± 0.1 Hz. (b) Conduction block overlay on Wheat Germ Agglutinin live staining of cell membranes with areas of interest marked. (c) Zoomed image of conduction block area from (b) area c. (d) Zoomed image of conduction block line from (b) area d. Cells for further analysis are marked on zoomed image c and d. (e) Unfiltered calcium fluctuations for cells indicated in micrograph c. (f) Unfiltered calcium fluctuations for cells indicated in micrograph d.

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  Fig. 8. Simultaneous optical recording of action potential and Ca2+ transients. (a) and (b) show activation maps obtained for action potentials and Ca2+ transients respectively. The maps using Ca2+ transients are determined from data three frames later because of the delay between action potentials and Ca2+ transient upstrokes (see graph (g)). (c) and (d) are the corresponding conduction block areas. The areas further analysed are indicated by circles of 10 μm diameter. (e) and (f) show the traces for action potentials (AP) and Ca2+ transients (CaT) respectively. The number on the right of each trace correspond to the areas shown in (c) and (d). All traces in (e) and (f) are unfiltered and at the same scale (no normalisation). (g) shows normalised traces of two action potentials (red) and Ca2+ transients (green) of area 4 in (c) and (d) showing the delay between the upstrokes. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)