Apocynum venetum Leaf Attenuates Myocardial Ischemia/Reperfusion Injury by Inhibiting Oxidative Stress

Apocynum venetum, a Chinese medicinal herb, is reported to be neuroprotective. However, whether Apocynum venetum leaf extract (AVLE) protects against ischemic myocardium remains elusive. Our present study was aimed to observe the effects of AVLE preconditioning on myocardial ischemia/reperfusion (MI/R) injury and to investigate the possible mechanisms. Rats were treated with AVLE (500 mg/kg/d, o.g.) or distilled water once daily for one week. Afterward, all the animals were subjected to 30 min of myocardial ischemia followed by 4 h of reperfusion. AVLE preconditioning for one week significantly improved cardiac function following MI/R. Meanwhile, AVLE reduced infarct size, plasma creatine kinase (CK)/lactate dehydrogenase (LDH) activities and myocardial apoptosis at the end of reperfusion in rat hearts. Moreover, AVLE preconditioning significantly inhibited superoxide generation, gp91(phox) expression, malonaldialdehyde formation and enhanced superoxide dismutase (SOD) activity in I/R hearts. Furthermore, AVLE treatment increased Akt and extracellular regulated protein kinases 1/2 (ERK1/2) phosphorylations in I/R rat heart. Either the Phosphatidylinositide 3-kinase (PI3K) inhibitor wortmannin or the ERK1/2 inhibitor PD98059 blocked AVLE-stimulated anti-oxidative effects and cardioprotection. Our study demonstrated for the first time that AVLE reduces oxidative stress and exerts cardioprotection against MI/R injury in rats.