Effects of Dantrolene on Myocardial Fibrosis and TGF-β1/Smad2 Signaling Pathway in Rats with Atrial Fibrillation
Objective:To investigate the effects of dantrolene on myocardial fibrosis and transforming growth factor-β1(TGF-β1)/Smad2 signaling pathway in atrial fibrillation rats.Methods:Seventy-two SD rats were randomly divided into blank control group,model group,dantrolene low-dose group,dantrolene high-dose group,positive control group,dantrolene high-dose+SRI-011381(TGF-βagonist)group,with 12 rats in each group.Dantrolene low-dose group and dantrolene high-dose group were intraperitoneally injected with 5 and 10 mg/kg dantrolene,respectively;rats in positive control group were given 20 mg/kg verapamil;rats in dantrolene high-dose+SRI-011381 group were intraperitoneally injected with 10 mg/kg dantrolene and 30 mg/kg SRI-011381,respectively;rats in blank control group and model group were intraperitoneally injected with equal volume of normal saline once a day for 4 weeks.After 4 weeks,except for the blank control group,the rats in the other groups were injected 1 mL/kg of acetylcholine-calcium chloride mixed solution(acetylcholine 66 μg/mL+calcium chloride 10 mg/mL)through the tail vein to construct the atrial fibrillation model.The rats in the blank control group were injected with equal volume of normal saline through the tail vein once a day for 1 week.One week later,ECG data were collected and the onset time of atrial fibrillation was recorded.The changes of left ventricular end-diastolic diameter(LVEDD),left ventricular shortening fraction(LVFS),left ventricular ejection fraction(LVEF),and left ventricular end-systolic diameter(LVESD)were detected by color Doppler ultrasound.Hematoxylin-eosin(HE)staining was used to detect pathological injury of myocardium in rats.Masson staining was used to detect myocardial fibrosis in rats.The expressions of type Ⅰ collagen(COL-Ⅰ)and type Ⅲ collagen(COL-Ⅲ)were detected by immunohistochemistry.The levels of tumor necrosis factor-α(TNF-α)and interleukin-1β(IL-1β)in myocardial tissue were detected by enzyme-linked immunosorbent assay(ELISA).The protein expression of TGF-β1,p-Smad2 andα-smooth muscle actin(α-SMA)were detected by Western Blot.Results:Compared with the blank control group,the model group rats showed arrhythmia,serious myocardial tissue pathological damage and fibrosis,positive expression of LVEDD,LVESD,COL-Ⅰ,COL-Ⅲ,IL-1β,TNF-α,and TGF-β1,p-Smad2,α-SMA protein expression increased,LVFS,LVEF decreased(P<0.05).Compared with model group,the change trend of corresponding indicators in dantrolene low-dose group,dantrolene high-dose group and positive control group were opposite to the above data,and the higher the concentration of dantrolene,the more obvious the corresponding change trend(P<0.05).SRI-011381 attenuated the inhibitory effect of high-dose dantrolene on myocardial fibrosis and inflammation in rats with atrial fibrillation.Conclusion:Dantrolene may reduce myocardial fibrosis and inflammation in rats with atrial fibrillation by inhibiting TGF-β1/Smad2 signaling pathway.
万方数据
