Fig. 3

Conduction, connexins, β-adrenergic stimulation and arrhythmogenesis in rat myocardial slices cultured for 24 h. a, b Representative images of longitudinal and transverse conduction maps of a 0 h rat myocardial slice. Black arrows show myocardial fibre direction. Yellow star = location of the stimulating electrode. Area of conduction map: 4.9 × 4.9 cm. c Longitudinal conduction velocity of rat myocardial slices cultured for 24 h (0 h N = 14, unloaded N = 10, SL = 1.8 N = 7, SL = 2.0 N = 6, SL = 2.2 and SL = 2.4 N = 8). d Conduction anisotropy ratio of rat myocardial slices cultured for 24 h (0 h N = 14, unloaded, SL = 2.2 and 2.4 N = 8, SL = 1.8 N = 7 and SL = 2.0 N = 6). e Representative images of rat myocardial slices stained for connexin 43. White arrow shows the longitudinal axis of cardiomyocytes. f Connexin 43 density in rat myocardial slices cultured for 24 h (0 h and SL = 2.4 N = 15/6, unloaded, SL = 1.8–2.2 N = 18/6). g Expression of genes associated with connexin 43 regulation and localisation at the intercalated disc (N = 3). h Isoproterenol dose response of rat myocardial slices cultured for 24 h (0 h, SL = 2.0–2.4 μm N = 7, unloaded N = 4 and SL = 1.8 μm N = 5). i Rate of aftercontractions with increasing concentration of isoproterenol of rat slices cultured for 24 h (0 h N = 8, unloaded, SL = 1.8–2.2 N = 6 and SL = 2.4 N = 7). j Arrhythmogenicity score of rat myocardial slices cultured for 24 h (0 h, unloaded, SL = 2.4 N = 8, SL = 1.8 and 2.0 N = 7 and SL = 2.2 N = 6). k Representative trace of an unloaded and SL = 1.8-μm rat myocardial slice developing a sustained tachyarrhythmia. l Expression of genes associated with the β-adrenergic stimulation (N = 3). Gene expression data from rat myocardial slices cultured for 24 h and expressed relative to 0 h rat myocardial slice gene expression N = number of myocardial slices. For Cx43 analysis, N = number of regions analysed/number of myocardial slices. Black dots represent individual data points. Mean ± standard error is shown on graphs. One-way analysis of variance (ANOVA) was used to determine whether there were any statistically significant differences between the means of groups. $, $$, $$$ = p value < 0.05, 0.01 and 0.001, respectively, compared with 0 h. *, **, *** = p value < 0.05, 0.01 and 0.001, respectively, between the two groups highlighted by a bar. Source data are provided as a Source Data file