[Mechanisms of Chinese herbs combined with ischemic postconditioning in protecting myocardium of rats from ischemia-reperfusion injury].

Objective: To observe the effects of Chinese patent medicines with the function of replenishing qi to activate blood (RQAB) plus ischemic postconditioning (IPoC) in protecting myocardium of rats from ischemia-reperfusion (I/R) injury, and to explore the possible mechanisms.
Methods: Seventy-five Sprague-Dawley rats were randomly divided into sham-operated group (the suture was penetrated around the left anterior descending coronary artery, but not tied, n=15), I/R group (30 minutes of in situ transient occlusion of the left anterior descending artery, followed by 1 hour of reperfusion, n=15), IPoC group (30 minutes occlusion of the left anterior descending artery, followed by 3 cycles of 10 s of reperfusion/10 s of ischemia before 1-hour reperfusion, n=15), RQAB plus IPoC group (pretreated with 0.162 g/kg Xinyue Capsule and 0.135 g/kg Xiongshao Capsule for 14 days, and treated with IPoC 2 h after the final gavage, n=15), fosinopril sodium plus IPoC group (pretreated with fosinopril sodium, 0.9 mg/kg, n=15). Serum creatine kinase-MB (CK-MB) activity and cardiac troponin T (cTnT) level were detected; myocardial infarction size was measured by nitrotetrazolium blue chloride staining; Toll-like receptor 2 (TLR2) and TLR4 in myocardial tissue were examined by immunohistochemical method; interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) levels in myocardial tissue were examined by enzyme-linked immunosorbant assay.
Results: Compared with the I/R group, myocardial enzymes and infarction size were decreased significantly in the IPoC group (P<0.01); expressions of TLR2 and TLR4 and levels of IL-1beta and IL-6 in myocardial tissues were also significantly lower than those in the I/R group (P<0.05). Compared with the fosinopril sodium plus IPoC group, expressions of TLR2 and TLR4 were decreased significantly in the RQAB plus IPoC group (P<0.05, P<0.01). Compared with IPoC, RQAB plus IPoC reduced the infarction size and the release of myocardial enzyme CK-MB (P<0.01), and decreased the expressions of TLR2 and TLR4 and the levels of IL-1beta and IL-6 (P<0.05, P<0.01) in myocardial tissues.
Conclusion: Pretreatment with Chinese herbs for nourishing qi and activating blood circulation can enhance the protective effect of IPoC on rat myocardial I/R injury, and its mechanism may be related to inhibition of TLR expression and expressions of the downstream proinflammatory cytokines.