Effect of ixeris sonchifolia pretreatment on expression of hypoxia-inducible factor-1α following myocardial injury induced by exhausting exercise in rats

Objective To evaluate the effect of ixeris sonchifolia pretreatment on the expression of hypoxia-inducible factor-1α (HIF-1α) following myocardial injury induced by exhausting exercise in rats. Methods Fifty-six healthy clean-grade male Wistar rats, weighing 200-220 g, were divided into 3 groups using a random number table method: control group (group C, n=8), exhausting exercise group (group E, n=24) and ixeris sonchifolia pretreatment group (group IS, n=24). In E and IS groups, the model of myocardial injury was established by exhausting swimming.In group IS, the rats were subjected to exhausting swimming after intraperitoneal ixeris sonehifolia 20 ml/kg.In E and IS groups, blood samples were taken from the inferior vena cava at 0, 6 and 24 h after exhaustion (T1-3) for determination of serum cardiac troponin I (cTnI) concentrations by enzyme-linked immunosorbent assay.The animals were sacrificed after anesthesia, and myocardial specimens were obtained for determination of the cell apoptosis index (by TUNEL) and expression of HIF-1α, Bax and Bcl-2 (by immunohistochemistry), and Bax/Bcl-2 ratio was calculated.The area of myocardial injury was observed using HBFP assay. Results Compared with group C, the area of myocardial injury, concentration of serum cTnl, Bax/Bcl-2 ratio and apoptosis index were significantly increased, and the expression of HIF-1α in myocardial tissues was up-regulated at each time point in E and IS groups (P<0.05). Compared with group E, the area of myocardial injury, concentration of serum cTnl, Bax/Bcl-2 ratio and apoptosis index were significantly decreased, and the expression of HIF-1α in myocardial tissues was down-regulated at each time point in group IS(P<0.05). Conclusion The mechanism by which ixeris sonchifolia pretreatment mitigates myocardial injury induced by exhausting exercise is related to inhibiting up-regulated expression of HIF-1α in myocardial tissues and reducing cell apoptosis in rats. Key words: Asteraceae; Hyperkinesis; Cardiomyopathies; Hypoxia-inducible factor 1, alpha subunit