Abstract:Aim To investigate the protective effect of remimazolam (Re) combined with thoracic sympathetic nerve block (TSNB) on myocardial ischemia/reperfusion (MI/R) rats. Methods Rats were randomly separated into control group, MI/R group, Re group, TSNB group, and Re+TSNB group, with 12 rats in each group. Except for the control group, the remaining rats were subjected to left anterior descending coronary artery (LAD) ligation to construct an MI/R model. In the Re group, 20 mg/kg Re was intraperitoneally injected 30 min before ischemia. In TSNB group, 0.2% ropivacaine 50 μL was injected into the thoracic epidural catheter 30 min before ischemia. In the Re+TSNB group, 20 mg/kg Re was intraperitoneally injected and 0.2% ropivacaine 50 μL was injected into the thoracic epidural catheter 30 min before ischemia. The control group and MI/R group were injected with normal saline only. Rats in each group were evaluated for cardiac function and infarct size. HE staining and TUNEL staining were applied to observe pathological changes in myocardial tissue and myocardial cell apoptosis. Serum myocardial injury markers creatine kinase (CK) and aspartate transaminase(AST), cardiac troponin(cTnI), myocardial inflammatory factors interleukin-8 (IL-8), tumor necrosis factor-α (TNF-α), and oxidative stress factors malondialdehyde (MDA), superoxide dismutase (SOD) were detected. Western blot was applied to detect the expression of IL-8, TNF-α,Bü lymphoblastoma-2-associated X protein(Bax), and B-lymphoblastoma-2 (Bcl-2) in myocardial tissue. Results Compared with the control group, the myocardial cells of rats showed edema and myocardial fiber disorder in the MI/R group, the left ventricular developmental pressure(LVDP), maximal left ventricular pressure rising rate(+dp/dtmax),maximal left ventricular pressure decreasing rate (－dp/dtmax), SOD activity, and level of Bcl-2 were significantly reduced, the myocardial infarction area, cell apoptosis rate, levels of cTnI, CK, AST, IL-8, TNF-α, MDA, and Bax were increased (P＜0.05). Compared with the MI/R group, the morphology of myocardial fibers and myocardial cells was significantly improved in the Re group, TSNB group and Re+TSNB group, the LVDP, ±dp/dtmax, SOD activity, and level of Bcl-2 were significantly increased, the myocardial infarction area, cell apoptosis rate, levels of cTnI, CK, AST, IL-8, TNF-α, MDA, and Bax were significantly decreased (P＜0.05). Compared with the Re group and TSNB group, the LVDP, ±dp/dtmax, SOD activity, and level of Bcl-2 were significantly increased in the Re+TSNB group, the myocardial infarction area, cell apoptosis rate, levels of cTnI, CK, AST, IL-8, TNF-α, MDA, and Bax were significantly decreased (all P＜0.05). Conclusion The combination of Re and TSNB may protect against MI/R injury by reducing myocardial infarction and myocardial cell apoptosis, and inhibiting inflammatory response and oxidative stress.
