Studies On Protective Effects And Mechanisms Of Salvianolic Acid B On Myocardial Ischemia/Reperfusion Injury

【Background】Coronary heart disease (CHD) is a major disease which threatens human health.Along with the wide application of coronary thrombolysis and coronary artery bypassgraft surgery (CABG), the subsequent myocardial ischemia/reperfusion (MI/R) injuryhas drawn much more attention among medical scientists. Numerous mechanismspropose to underlie the pathology in MI/R injury, including free radical injury, calciumoverload, inflammation and injury of vascular endothelial cells. Thus, searching forcardioprotective agents with alteration the above mechanism probably represents an idealstrategy to develop safe and effective agents for MI/R injury treatment.Traditional Chinese medicine (TCM) has demonstrated a good practice and shows abright future in the therapy of MI/R injury. Recent studies have focused more onDanshen (Radix Salvia miltiorrhiza). Modern pharmacological research displays thatDanshen has expanded coronary artery, prevent myocardial ischemia and myocardial infarction, improve microcirculation, reduce myocardial oxygen consumption, and arewidely used and clinical treatment for diseases of the cardiovascular system. Salvianolicacid B (Sal B) is the most abundant component in aqueous extracts of the Danshen and ispresent mainly as a magnesium salt-magnesium lithospermate B (MLB). Studies havereported that Sal B has a protective effect on MI/R injury. However, up to now, themechanisms of Sal B are far from clear in the process of MI/R injury. The aim of thisstudy is to investigate the effects of Sal B against MI/R injury and to explore its potentialmechanisms of cardioprotection.【Objectives】This study aims to investigate the protective effects and mechanisms of Sal B invivo and in vitro using the model of MI/R in rat and SI/R-induced H9c2ratcardiomyocytes.【Methods】Part1MI/R (30min/3h) injury model in rat.1) Heart function test indexes: LVSP, LVEDP,+dp/dtmax,-dp/dtmax;2) Myocardial injury serum biochemical indexes: cTnI, CK-MB;3) Antioxidant serum biochemical indexes: SOD, MDA;4) Anti-inflammatory serum biochemical indexes: IL-1, IL-6, TNF-α;5) Evan Blue&TTC myocardial infarction area indexes: RZ(%), IZ(%);6) Hematoxylin&Eosin myocardial tissue pathologic change;7) Myocardial enzyme indexes: SOD, MPO;8) Western blot: Nrf2, NF-κB.Part2SI/R (2h/3h) injury model in H9c2cardiomyocytes.1) Myocardial cell survival rate: MTT;2) Cell damage enzyme: CK-MB, LDH;3) Apoptosis assays: Annexin V-FITC/PI, Hoechest33258;4) Western blot: Akt, e-NOS.【Results】Part1: MLB can improve heart function changes; inhibit myocardial injury markerenzymes cTnI, CK-MB; reduce lipid oxidation products MDA content; increasevitality of superoxide dismutase SOD; suppress serum inflammatory cytokines IL-1,IL-6and TNF-α; reduce myocardial infarct size; reverse the pathological changes of myocardial tissue; increase activity of SOD; reduce MPO vitality; suppress themyocardial tissue level of NF-κB and elevate Nrf2expressions.Part2: MLB can improve cell viability; reduce CK-MB, LDH levels;inhibit H9c2cardiomyocyte apoptosis; elevate p-Akt, p-eNOS levels.【Conclusions】Sal B possesses marked potent cardioprotective effects on MI/R injury in vivo andin vitro, which is related to its ability of anti-inflammation, anti-oxidation andanti-apoptosis.