Study On The Intervention Of Myocardial Ischemia Injury By Sodium Butyrate Based On PKM2 In Rats

Acute myocardial ischemia is caused by caused by acute, persistent coronary artery occlusion, which without proper treatment will lead to local myocardial infarction. Due to its acute and dangerous characteristics, and high mortality, it is considered to be the leading cause of sudden death in the elderly population. However, the incidence rate in the younger generations is increasing in our country, with higher mortality, and severely threatens people’s lives. Currently, drug therapy is considered as primary intervention in treating myocardial ischemia. Meanwhile, reperfusion therapy including coronary artery interventional therapy is also recommended. However, how to improve the therapeutic effect and prognosis of myocardial ischemia while reducing adverse reactions is still a key problem.Sodium butyrate is a type of histone acetylase inhibitor, can improve the histone acetylation level, studies have shown that sodium butyrate can inhibit the proliferation of tumor cells and promote the aging, apoptosis of cancerous cells. Sodium butyrate might exert those effects through regulating histone acetylation level. And anti-cancer properties of sodium butyrate have been evaluated in clinical studies. It’s been previously reported that sodium butyrate may exert cytoprotective effects in ischemic myocardium, however, the detailed mechanism and signaling pathways are remained to be illustrated.Pyruvate kinase(PK) is the major rate-limiting enzyme in the glycolytic pathway. It could catalyze its upstream substrate, phosphoenolpyruvic acid(PEP) into pyruvic acid while producing one molecule of ATP. The pyruvate kinase M2(PKM2), one isoenzyme of PK, is overexpressed in proliferating cells, especially in tumor cells.The conversion between tetramer and dimer of PKM2 decides whether the pyruvic acid generated via glycolysis is used for energy production or in biosynthesis.Further studies have elucidated the important function of PKM2 in tumor metabolism and it has been evaluated in clinical studies as a target for cancer therapy. However, the emerging role of PKM2 in myocardial energy metabolism have drawn much attention.Objective: The present study sought to illustrate the protective effects of sodium butyrate after myocardial ischemia injury. And to observe whether this effect depends on PKM2 activity. To explore of the whether sodium butyrate functions through PKM2, to regulate myocardial energy metabolism, therefore, exerting its protective effects after myocardial ischemia injury.Methods: Myocardial ischemia rat model was established, and sodium butyrate was applied to test possible protective effects after myocardial ischemia injury. To study the dynamic of PKM2, western blotting was used to detect PKM2 levels at various time points(1d, 2d, 3d,7d). The expression of PKM1 and PKM2 in normal and ischemic myocardium were evaluated to study the relation between those two proteins after ischemic myocardial injury. PKM2 inhibitor Shikonin was applied to test whether the protective effects of sodium butyrate requires PKM2 activity.Immunofluorescence staining were used to study the effect of sodium butyrate on PKM2 subcellular localization. Pyruvate kinase activity kit was used to study the dynamic changes in PKM2 activity after myocardial ischemic injury. ATP level was determined to evaluate the effect of sodium butyrate on myocardial energy metabolism.Results: It was found that sodium butyrate reduce myocardial ischemia rat myocardial infarction area, reduce the serum myocardial enzyme AST, CK, LDH, reduce MDA content and increase SOD activity.By Western Blot experiments found that myocardial ischemia after 1, 2, 3 and 7 days PKM2 expression quantity increase;Using Western Blot and immunofluorescence technology found that give sodium butyrate increase ischemic myocardial tissue PKM2 expression, with 2 days group expression quantity highest, sodium butyrate may promote PKM2 expression after myocardial ischemia.It was found that sodium butyrate can improve myocardial ischemia rats pyruvate kinase activity, increase the ATP content.Choose the specific inhibitors of PKM2 alkannin found that sodium butyrate alkannin could antagonism to reduce the effects of myocardial infarction area, and the role of CK, AST and LDH, suggest to give alkannin PKM2 after aggravating the degree of myocardial injury.By Western Blot experiments found that after giving inhibitors alkannin cut PKM2 expression in myocardial tissue, weakening the effect of sodium butyrate increased PKM2 expression, prompt the protective effects of sodium butyrate on acute myocardial ischemia with the participation of PKM2.Conclusions: 1. Sodium butyrate has protective effect on acute myocardial ischemic injury.2. PKM2 expression in ischemic myocardial tissue increased, and the second day of the most obvious after ischemia.3. Sodium butyrate can increase the expression of PKM2, enhance its activity, increase the amount of ATP.4. PKM2 inhibitors Shikonin partly can affect the effect of sodium butyrate, hints of sodium butyrate on ischemic myocardial protection part by regulating the PKM2.