Exercise preconditioning improves electrocardiographic signs of myocardial ischemic/hypoxic injury and malignant arrhythmias occurring after exhaustive exercise in rats

Figures

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  Figure 1. Experimental protocol24. C, control group; EEP, early exercise preconditioning group; LEP, late exercise preconditioning group; EE, exhaustive exercise group; EEP + EE, early exercise preconditioning plus exhaustive exercise group; LEP + EE, late exercise preconditioning plus exhaustive exercise group.

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  Figure 2. ECG analysis results in rats. (a) The ECG waves in rats (40 mm/mV, 400 mm/s). (b) HR results in each group of rats (LSD test). (c) Changes in ST segments on ECG (K-W test). (d) Changes in T waves on ECG (K-W test). (e) Changes in QTc intervals on ECG (LSD test). The elevation of the ST segment in group EE was significantly higher than that in group C, and the ST segments of group EEP + EE and group LEP + EE were significantly lower than that of group EE (a,c). The T wave of group EE was significantly higher than that of group C; the T waves were significantly lower in group EEP + EE and group LEP + EE than in group EE (a,d). The QTc interval in group EE was obviously prolonged compared with that in group C, and the QTc intervals in group EEP + EE and group LEP + EE were obviously shortened compared with that in group EE (a,e). Compared with that of rats in group C, the HR of rats in group EE was significantly higher. Compared with that of rats in group EE, the HR of rats in group EEP + EE and group LEP + EE was significantly lower. The results suggested that EP could significantly decreased the HR during exhaustive exercise (b). The results suggested that EP could effectively…

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  Figure 3. Results of plasma cTnI measurement (K-W test). Compared with that in group C, the plasma cTnI level was significantly higher in group EE. Compared with that in group EE, the plasma cTnI level was significantly lower in group EEP + EE and group LEP + EE. The results suggested that exhaustive exercise induced myocardial injury and that EP had a protective effect against exhaustive exercise-induced myocardial injury.

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  Figure 4. Analysis of the myocardium in HBFP staining images. (a) The results of HBFP staining of the myocardium (scale bar: 20 μm). There were a large number of scarlet-stained cardiomyocytes in group EE. The number of scarlet-stained cardiomyocytes was obviously reduced in the EEP + EE and LEP + EE groups. (b) The analysis of IHA in HBFP staining images (K-W test). (c) The IOD of HBFP staining images (K-W test). (d) The MOD of HBFP staining images (K-W test). The IHA, IOD, and MOD were significantly elevated in group EE. Compared with those in group EE, the IHA, IOD, and MOD in group EEP + EE and group LEP + EE were significantly lower. The results suggested that exhaustive exercise induces severe ischemic/hypoxic injury in the myocardium and that EP can effectively mitigate the ischemic/hypoxic injury caused by exhaustive exercise.

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  Figure 5. Correlation analysis of ST segments and T waves with HBFP staining. The results of correlation analysis of ST segments (a–c) and T waves (d–f) with HBFP staining in group EE (a,d), group EEP + EE (b,e) and group LEP + EE (c,f). The results suggested that ST segments and T waves on ECG had a strong positive correlation with HBFP staining.