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  • br Materials and methods br Results br

    2020-03-17


    Materials and methods
    Results
    Discussion and conclusion The cardiac hypertrophy model can be established by two methods: drug induction and operation. The drug induction method is simple, while the operation method is closer to the real development of the disease. In this experiment, according to the methods of previous authors [15] and proper procedures, we surgically operated the mice on the left side of the midline of the abdomen, above the thigh, and after the incision under the ribs, then gently tap the kidneys and spleens were gently tapped with tweezers. The abdominal Nexturastat A (usually covered by fat and peritoneum) is found along the renal vein and adrenal artery. The fat and peritoneum was gently wiped off with a small cotton ball, and the abdominal aorta is carefully separated with a glass hand. The advantage of this method is that it can quickly locate the abdominal aorta. The entire process takes a short time and very little bleeding occurs, which improves the postoperative survival rate. Left ventricular remodeling caused by stress overload leads to increased heart indexes, cardiac cell size, ventricular dilatation, changes in myocardial interstitium and perivascular fibrosis [19,20]. In recent years, a large number of studies have made great efforts in the development of new medications [21,22] and the identification of new signaling pathways [23,24] related to cardiac hypertrophy. On the basis of previous studies, this experiment further investigates the eNOS-NO signaling pathway to verify the dependence of MHBFC on eNOS genes in the treatment of stress overload cardiac hypertrophy. The results showed that MHBFC significantly decreased the heart index, the area of cardiomyocytes, and the myocardial and perivascular fibrosis of wild-type mice. However, there was no significant effect of the treatment on eNOS knockout mice. Therefore, the results showed that MHBFC is dependent on the eNOS gene in reversing the reconstructive index and myocardial fibrosis, but how the eNOS gene reverses and improves these changes requires further study. For example, whether the eNOS gene inhibits the calcium influx by increasing the concentration of cGMP in the cardiac myocytes to ameliorate cardiac hypertrophy remains to be studied in our next experiment. ANP and BNP are markers for the clinical diagnosis of hypertrophy and cardiac insufficiency, and they can predict the severity and prognosis of the disease [25,26]. In addition, studies have shown that ANP, BNP, and β-MHC are associated with hypertension, myocardial infarction, cardiomyopathy, and myocardial interstitial fibrosis [[27], [28], [29]]. When ventricular volume load and pressure overload increase, ANP and BNP [30] are released from cardiac myocytes, and the levels of BNP and β-MHC increase when endothelial dysfunction occurs. Early studies have shown that elevated levels of SAA in the body were associated with increased incidence of cardiovascular and lifestyle-related diseases such as obesity, diabetes [31], and metabolic syndrome [32]. All these studies indicate that the levels of ANP, BNP, β-MHC, and SAA will increase when cardiac hypertrophy occurs. In this experiment, the hypertrophic gene level in the model group increased significantly 6 weeks after AAB surgery and then decreased significantly after the treatment of MHBFC in wild-type mice. However, the hypertrophic gene level of all groups showed different degrees of increase in eNOS knockout mice, and there were no significant changes after treatment with MHBFC. These results indicate that MHBFC depends on eNOS genes in the treatment of pressure overload cardiac hypertrophy. In this study, our results showed that after the eNOS gene was knocked out in the background of wild-type mice, the eNOS knockout mice in the sham operation group also developed cardiac hypertrophy, which had the same symptoms as the mice in the model group, such as the increase of the heart index, hypertrophy of cardiac myocytes, and increased deposition of collagen. After MHBFC treatment, the cardiac hypertrophy indexes of wild type-mice were more obviously recovered than those of the model group, but the effect of MHBFC treatment on eNOS gene knockout mice was not obvious, indicating that MHBFC depends on the presence of eNOS genes to reverse cardiac hypertrophy. And further studies mentioned the correlation of MHBFC, eNOS-NO signaling pathway and cardiac hypertrophy have been done, the results indicated that MHBFC could increase eNOS protein phosphorylation and eNOS gene expression by increasing PI3K and Akt protein phosphorylation and PI3K and Akt gene expression, and activated the eNOS-NO signaling pathway, increased eNOS enzyme activity, catalyzed the generation of protective NO, thereby protecting against myocardial damage and reversing cardiac hypertrophy. And these results will be reported in another manuscript.