Cardiac remodeling and arrhythmogenesis are ameliorated by administration of Cx43 mimetic peptide Gap27 in heart failure rats

Figures

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  Figure 1. Effect of Gap27 on echocardiographic parameters in AV-Shunt rats. a Representative echocardiographic image of the left ventricle from one ShamScr rat, one ShamGap27 rat, one AV-ShuntScr rat and one AV-ShuntGap27 rat at 4th and 8th weeks post-AV-Shunt (before and after treatment with Gap27, respectively). Summary data of LVEDV b and LVESV c parameters. Values are shown as mean ± SEM. Data were analysed with 2-way ANOVA followed by Sidak post hoc analysis. *p < 0.05 vs. ShamScr 4 wk; +p < 0.05 vs. ShamGap27 4 wk; †p < 0.05 vs. AV-ShuntScr 4 wk; ‡p < 0.05 vs. AV-ShuntGap27 4 wk; #p < 0.05 vs. ShamScr 8 wk; §p < 0.05 vs. AV-ShuntScr 8 wk. n = 8 animals per group.

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  Figure 2. Effect of Gap27 on cardiac function in AV-Shunt rats. (a) End-systolic pressure-volume relationship (ESPVR) and (b) End-diastolic pressure-volume relationship (EDPVR) estimated by single-beat analysis from one ShamScr rat, one ShamGap27 rat, one AV-ShuntScr rat and one AV-ShuntGap27 rat at 8 wk. Note that Gap27 treatment significantly improves systolic and diastolic cardiac function measured by the slope (EES) of ESPVR and b coefficient from EDPVR in AV-Shunt rats, respectively. In addition, Gap27 treatment improves ESPVR in Sham treated rats. (c,d) Summary data of the effects of Gap27 treatment on ESPVR and Volume at Pressure 0 mmHg (Volume-0) (predictors of EDPVR). (e,f). Summary data of the left ventricle end-diastolic pressure and left ventricle end-systolic pressure. Gap27 treatment reduced LVEDP in AV-Shunt rats, but not LVESP. Values are shown as mean ± SEM. Data were analysed with one-way ANOVA followed by Sidak post hoc analysis. *p < 0.05 vs. ShamScr; +p < 0.05 vs. ShamGap27; †p < 0.05 vs. AV-ShuntScr. n = 8 animals per group.

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  Figure 3. Gap27 administration improves cardiac arrhythmogenesis in AV-Shunt rats. (a) Representative tachograms from one ShamScr rat, one ShamGap27 rat, one AV-ShuntScr rat and one AV-ShuntGap27 rat obtained from EKG recordings. (b) Summary data show the incidence of ventricular premature beats (VPB). Note that Gap27 treatment reduces the arrhythmia incidence in AV-Shunt rats. (c) Summary data show the arrhythmic score. (d) Representative EKG recordings from one ShamScr rat, one ShamGap27 rat, one AV-ShuntScr rat and one AV-ShuntGap27 rat. Quantification of (e) PR interval, (f) P duration, (g) QRS interval and (h) RR interval. Values are shown as mean ± SEM. (b,e–h) Data were analysed with one-way ANOVA followed by Sidak post hoc analysis. c Data were analysed with Kruskal-Wallis test followed by Dunn post hoc analysis. *p < 0.05 vs. ShamScr; +p < 0.05 vs. ShamGap27; †p < 0.05 vs. AV-ShuntScr. n = 5–8 animals per group.

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  Figure 4. Gap27 reduces cardiac hypertrophy, fibrosis and pulmonary congestion in AV-Shunt rats. (a) Representative images of heart cross-sections obtained from one ShamScr rat, one ShamGap27 rat, one AV-ShuntScr rat and one AV-ShuntGap27 rat. Scale bar 5 mm. (b) Representative images of Masson’s trichome staining in heart cross-sections from one ShamScr rat, one ShamGap27 rat, one AV-ShuntScr rat and one AV-ShuntGap27 rat. Scale bar 25 µm. (c) Representative picrosirius red staining images in the left ventricle from one ShamScr rat, one ShamGap27 rat, one AV-ShuntScr rat and one AV-ShuntGap27 rat. Scale bar 250 µm. (d) Summary data of heart weight/body weight ratio. (e) Summary data show the cardiomyocyte cross-sectional area. (f) Summary data showing collagen content in the left ventricle. (g) Summary data show the lung congestion calculated as the lung wet/dry ratio. Values are shown as mean ± SEM. (d–f) Data were analysed with one-way ANOVA followed by Sidak post hoc analysis; (g) Data was analysed with Kruskal-Wallis test followed by Dunn post hoc analysis. *p < 0.05 vs. ShamScr; +p < 0.05 vs. ShamGap27; †p < 0.05 vs. AV-ShuntScr. n = 6–8 animals per group.

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  Figure 5. Effects of Gap27 on Cx43 protein expression in AV-Shunt rats. (a) Representative immunoblot of Cx43 expression in the rat left ventricle. (b) Densitometry analysis of Cx43 total relative expression. GADPH expression was analysed as the loading control. (c) Representative immunofluorescence of left ventricle labelled with anti-Cx43 antibody (green) and β-actin (pink) from one ShamScrrat, one Shamgap27 rat, one AV-ShuntScr rat and one AV-ShuntGap27 rat. Scale bar 25 µm. Note that in AV-Shuntscr animals the patterns of Cx43 staining is lateralized compared to Shamscr animals. Values are shown as mean ± SEM. Data were analysed with Kruskal-Wallis test followed by Dunn post hoc analysis. *p < 0.05 vs. ShamScr. n = 8 per group.