| Objective: By studying the production of rat myocardial infarction model,the effects of Ghrelin on cardiac function,ventricular remodeling,cardiac electrophysiology,cardiac tissue and sympathetic nerve discharge in rats with acute myocardial infarction and its constitutive mechanism were discussed.Ghrelin provides a theoretical basis for the treatment of heart failure.Methods: Thirty male Sprague-Dawley rats were randomly divided into three groups: sham operation group(Sham group: n=6),chronic heart failure group(CHF group,n=12)and exogenous injection of ghrelin intervention group(CHF+G).Group,n=12),the sham operation group was treated with the left coronary artery but not the ligation,the chronic heart failure group and the exogenous Ghrelin group were used to ligature the left anterior descending coronary artery of the rat.Among them,the CHF+G group was given subcutaneous injection of 100ug/kg Ghrelin one week later,and the other two groups were injected with the same amount of normal saline.After 5 weeks,ECG and echocardiography were performed first.The QT interval,QRS width,PR interval,P-wave width and other parameters of the rat electrocardiogram were measured,and the left ventricular ejection fraction was measured by cardiac color Doppler ultrasound.(Left Ventricular Ejection Fraction,LVEF)and Left Ventricular Fractional Shortening(LVFS),arterial blood pressure and left ventricular pressure were measured by catheterization into the common carotid artery,by programmed electrical stimulation(Programmed Electrical Stimulation,PES)measured the ventricular refractory period(VERP)and induced various ventricular arrhythmias,measured the epicardial single-phase action potential(APD),and recorded the phenomenon of cervical sympathetic discharge.Finally,the rats were sacrificed,and the hearts were taken out and subjected to HE staining and Masson staining,respectively.The morphology and size of myocardial cells,the changes of interstitial edema and the degree of inflammatory infiltration were studied by HE staining.Cardiac cells,interstitial fibrosis and vascular remodeling were observed by Masson staining,and Wall Thickness of Vessel(WTV)and Collagen Volume Fraction(CVF)were measured.Results: SHAM group,CHF group and CHF+G group survived at 6th,10 th and 8th,respectively.(1)Compared with the SHAM group,the body weight,heart weight and body weight ratio of the CHF group were significantly increased(P<0.05).The weight of the CHF group was significantly different from that of the CHF group,but the heart weight and heart.The body ratio was significantly lower than that in the CHF group(P<0.05).The Left Ventricular Ejection Fraction(LVEF)and the Left Ventricular Fractional Shortening(LVFS)in the CHF group were compared with the SHAM group.Significantly reduced(P <0.05);The use of exogenous ghrelin injection in the CHF group can significantly improve these two indicators(P <0.05),and the exogenous ghrelin injection CHF group can significantly reduce the mean arterial pressure,can also significantly reduce the left ventricle of heart failure rats after myocardial infarction End-diastolic pressure(P<0.05),increased rate of pressure change in the isovolumic systolic phase of the left ventricle(P<0.05);By HE staining,the myocardial cells of the CHF group were significantly increased compared with the SHAM group,and the infiltration of inflammatory cells and interstitial edema were observed.The pathological symptoms were significantly improved by exogenous ghrelin injection in the CHF group.By Masson staining,it was found that CHF rats showed significant myocardial fibrosis and vascular remodeling compared with SHAM rats,and exogenous injection of ghrelin in CHF group significantly improved the above symptoms.(2)Cardiac electrophysiological findings showed that the electrocardiogram QRS wave was significantly broadened after 5 weeks of CHF rats,and the QT interval was significantly prolonged.The remaining ECG parameters such as P wave width and PR interval were not statistically different between the groups.Through the procedural electrical stimulation,the incidence of various ventricular arrhythmia was significantly increased,the sympathetic nerve activity was significantly increased,the effective refractory period of the ventricle was prolonged,the APD90 in the infarcted area and the non-infarcted area was prolonged,and the frequency of APD electrical alternation occurred.Decreased,and exogenous injection of ghrelin can significantly improve the above electrophysiological abnormalities(P<0.05).Conclusion: 1.A stable myocardial infarction model can be made by ligation of the left anterior descending coronary artery,which in turn produces chronic heart failure.2.Exogenous injection of ghrelin can improve ventricular remodeling and cardiac function in rats with heart failure after myocardial infarction by inhibiting cardiomyocyte apoptosis,and can improve myocardial fibrosis and inflammatory cell infiltration.3,exogenous injection of ghrelin can also reduce the abnormal sympathetic discharge activity of rats with chronic heart failure and improve their abnormal ECG parameters,cardiac surface electrophysiological indicators. |
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