| OBJECTIVE:1.To establish a myocardial infarction model by surgically ligating the left anterior descending coronary artery?LAD?of rats,observe the24-hour dynamic electrocardiogram of rats and analyze the ST segment evolution characteristics.2.To observe the effect of sugarcane leaf polysaccharide on ventricular remodeling in rats with myocardial infarction.METHODS:Forty healthy SD rats,male,weight 230±20g.They were randomly divided into experimental group?sugarcane leaf polysaccharide group?,model control group and sham operation group.At 24h and 30min before surgery and 4 weeks after surgery,the experimental group was given sugarcane leaf polysaccharide?4g/L?,and was administered intragastrically at a dose of 1mL/100g per rat body weight,once/d.Model control group and sham operation group were given the same amount of physiological saline.In the experimental group and the model control group,the LAD was ligated by surgery to establish a myocardial infarction model.The sham operation group had the same surgical procedure,but did not knot after threading under the LAD.Electrocardiograms were recorded before and after thoracotomy to observe the ST segment deviations of limb leads?I,II,aVL,aVF?and chest leads?V1,V2,V5?.Postoperative ST elevation was?0.1mV than the ones of preoperatively,suggesting that the model was successful.After the experimental group and the model control group were successfully modeled,install the dynamic electrocardiogram,observation of the evolution process of the dynamic electrocardiogram,analyze the electrocardiogram of the limb leads?I,II,aVL,aVF?and chest leads?V1,V5?at 1 hour intervals of 24 hours and observe the ST segment deviation.Dynamic electrocardiogram was directly installed after the operation in the sham operation group.4 weeks after the operation,the thoracic incision was performed along the original incision,Taking blood from the apex,measure the levels of Angiotensin II?ANG-II?.The heart of the rat was removed,measurement of cardiac mass index and left ventricular mass index.The heart of the rat was dissected by resection of the myocardium above the ligation line and the heart of the rat was removed for pathological examination,get some myocardial tissue of the infarcted border zone.Measure the levels of superoxide dismutase?SOD?and malondialdehyde?MDA?.RESULTS:The survival rate from the rat to the experimental endpoint was 13 in the experimental group,9 in the model control group,and 8 in the sham operation group.1.Dynamic electrocardiogram results:?1?The evolution of 24h electrocardiogram after myocardial infarction:The dynamic electrocardiogram recorded that the fusion of the ST segment and the T wave was raised up archwardly,There is no abnormal Q wave at this time.A few hours later,abnormal Q waves began to appear,and the ST segment continued to rise to the top,After that,the elevated ST segment began to slowly decline and continued until the end of the monitoring.?2?ST segment elevation:The ST segment of dynamic electrocardiogram of the rats in sham operation group was not significantly elevated compare the ones before surgery.The amplitude of ST segment elevation in lead I,lead II,and lead V5 was lower in the experimental group than in the model control group.The difference was statistically significant?P<0.05?.There was no significant difference between the other observation leads compare to the model control group?P>0.05?.2.Pathological examination results:in the sham operation group,the myocardial fibers were regular,abundant in cytoplasm,and the size of the myocardial cell nuclei was uniform.It was a long ellipse and located in the center of the muscle fibers.Cardiomyocytes have no atrophy or hypertrophy,no eosinophil staining and necrosis.The rats in the model control group showed fibrous tissue proliferation,disordered arrangement of fibers,marked edema of myocardial interstitium,and more connective tissue hyperplasia in the interstitium.The sugarcane leaf polysaccharide group had a regular arrangement of myocardial fibers,some of the cell morphology was irregular,and the cytoplasm was lightly stained.A small amount of connective tissue hyperplasia and a small amount of inflammatory cell infiltration were observed in the myocardial stroma,and the myocardium fibers were not significantly thickened.3.Cardiac mass index and left ventricular mass index:Compared with sham operation group,the cardiac mass index and left ventricular mass index increased in the model group?P<0.05?;.Compared with the model group,the cardiac mass index and left ventricular mass index decreased in the experimental group.The difference was statistically significant?P<0.05?.4.Angiotensin II?ANG-II?level:Compared with the sham operation group,the plasma ANG-II concentration in the model group increased,and the difference was statistically significant?P<0.05?,Compared with the model group,the plasma ANG-II concentration in the experimental group decreased,and the difference was statistically significant.The difference was statistically significant?P<0.05?.5.Superoxide dismutase?SOD?and malondialdehyde?MDA?levels measurement:Compared with sham operation group,the SOD level in the model group was decreased,and MDA level was increased?P<0.05?.Compared with the model control group,the SOD level in the experimental group was increased and the MDA level was decreased.The difference was statistically significant?P<0.05?.CONCLUSION:1.Dynamic electrocardiogram?ECG?was used to detect24h after myocardial infarction in rats.ST segment elevation was most obvious in limb leads?I,II,aVL?and chest lead?V1,V5?.2.Sugarcane leaf polysaccharides can reduce the ST segment elevation in 24h of myocardial infarction rats,and have some protective effects on myocardium.3.The sugarcane leaf polysaccharides to a certain extent,can improve the ventricular remodeling in rats and its possible mechanism is by reducing the ANG-II concentration,increased SOD content and decreased the level of MDA play effect on ventricular remodeling. |
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