The Effect And Molecular Mechanism Of TashinonⅡA On The Hypertrophic Cadiocyte Due To Abdominal Aorta Stenosis In Rats

Cardiac hypertrophy is an adaptive response of the heart to virtually all forms of cardiac diseases, including those arising from hypertension, mechanical load, myocardial infarction ,cardiac arrhythmias, endocrine disorders, and genetic mutations in cardiac contractile protein genes. While the hypertrophic response is initially a compensatory mechanism that augments cardiac output, hypertrophy can lead to dilated cardiomyopathy, heart failure and sudden death. cardiac hypertrophy was an absolute and dangerous factor that affected mortality and morbidity for cardiovascular diseases.Left ventricular weight rise in patients with cardiac hypertrophy. Cardiac hypertrophy was not only a pathophysiological process, but also a discompensatory change that affected short-term and long-term prognosis. Nowdays drugs for curing cardiac hypertrophy mostly have angiotenesin converting enzyme inhibitors ,angiotensin receptor blocker and calcium channel antagonist. But these drugs have their limit for some adverse reaction. So it is important to look for several drugs which have good therapeutic effect and little side effect in the long-term cure for myocardial hypertrophy.Tanshinoneâ…¡A is the main lipid soluble component of danshen, a kind of traditional Chinese drug. Now it has been found that tanshinoneâ…¡A could alleviate and reverse left ventricular hypertrophy causing by hypertension, but its mechanism is still unknown.In this study, we would construct the model of myocardial hypertrophy in hypertensive rats caused by abdominal aorta constriction and compare tanshinoneâ…¡A with an angiotensin receptor inhibitor-valsartan, a classical drug for resisting cardiac hypertrophy to explore the molecular biological mechanism for tanshinoneâ…¡A reversing myocardial hypertrophy. Part one : the ultrasound imageological and pathomorphological effect of tanshinoneâ…¡A on hypertrophic myocardium due to abdominal aorta stenosis in ratsObjective: To study the effect of tanshinoneâ…¡A on hypertrophic myocardium caused by abdominal aorta stenosis in rats.Methods: Taking 40 rats who were suffered abdominal aorta constriction and 8 rats who were suffered artificial surgery. 4 weeks later, these rats would be divided into 4 groups: myocardial hypertrophy, low dose tanshinoneâ…¡A treatment (10mg/kg/d peritoneal injection), high dose tanshinoneâ…¡A treatment (20mg/kg/d peritoneal injection) and valsartan treatment (10mg/kg/d intragastric administration). After accepting therapy for 8 weeks, to measure the thickness of posterior ventricular wall and interventricular septum and left ventricular ejection fraction(EF) by echocardiogram ; then to take the tissue of left ventricle to detect left ventricular mass index ( LVMI) and myocardial fiber dimension (MFD) by pathological section and HE stain.Results :1. The blood pressure in the group of myocardial hypertrophy and tanshinoneâ…¡A treatment (low and high dose) was obviously higher than that in the group of artificial surgery and valsartan treatment (p<0.01). But it was not different between myocardial hypertrophy group and tanshinoneâ…¡A treatment (low and high dose) groups (p>0.05).2. The thickness of interventricular septum in the groups of tanshinoneâ…¡A and valsartan was more than that in artificial surgery (p<0.05), but less than that in myocardial hypertrophy. And two tanshinoneâ…¡A treatment groups had similar result(p>0.05), but they both were thicker than valsartan treatment group.3. There were not significant difference about thickness of posterior left ventricle among two tanshinoneâ…¡A treatment groups and valsartan treatment group(p<0.05). They were all obviously less than that in myocardial hypertrophy group(p<0.01), but did not get to normal lever(p<0.05).4. The EF value in all groups were in normal range(>60%). Though it was not found heart failure in myocardial hypertrophy group, the EF value in this group were less than that in other groups(p<0.05). And EF value in tanshinoneâ…¡A groups was less than that in valsartan group(p<0.05).5. There were not significantly different in LVMI and MFD between two tanshinoneâ…¡A treatment groups(p>0.05). MFD in valsartan group and two tanshinoneâ…¡A groups were obviously less than that in myocardial hypertrophy group(p<0.01) and more than that in artificial surgery group(p<0.05); and two tanshinoneâ…¡A groups more than valsartan group(p<0.05).Conclusion: The effect of tanshinoneâ…¡A on myocardial hypertrophy was not dependent on blood pressure. As angiotensinâ…¡receptor antagonist-valsartan did , tanshinoneâ…¡A could block and reverse the development of myocardial hypertrophy, but its was a little weaker . Part two: The effect of tanshinoneâ…¡A on angiotensin receptor and free calcium ion in hypertrophic myocardium of rats due to abdominal aorta constriction.Objective: To explore the molecular biological mechanism about tanshinoneâ…¡A reversing left ventricular hypertrophy, it would be studied how tanshinoneâ…¡A gave an impact to angiotensin receptor and free calcium ion in hypertrophic myocardium of rats due to abdominal aorta constriction.Methods: To detect mRNA and protein's expression of AT1 and AT2 receptors in left ventricular tissues of all groups by RT-PCR and Western blotting.Results:1. The mRNA and protein's expression of AT1 receptor in myocardial hypertrophy group were obviously more than that in other groups(p<0.01); there were no difference within two tanshinoneâ…¡A groups(p>0.05), but tanshinoneâ…¡A groups was higher than valsartan group(p<0.05). The genic expression in these three groups did not recover to normal lever( artificial surgery group)(p<0.05).2. The mRNA and protein's expression of AT2 in valsartan group was more than that in other groups(p<0.05), and there were no difference among the other groups(p>0.05).3. The concentration of calcium ion in myocardial hypertrophy group was highest( VS other groups, p<0.01); and that in the two tanshinoneâ…¡A groups and artificial surgery group had not statistically different(p>0.05) , but they were lower than that in valsartan group(p<0.05).Conclusion: Tanshinoneâ…¡A and Valsartan both could resist the myocardial hypertrophy by downregulating the genic expression of AT1 receptor and blocking the inflow of calcium ion in cadiocyte. Moreover, AT2 receptor may participate the effect of lowering blood pressure and reversing hypertrophy as for valsartan. Part three: the effect of tashinone on the nitric oxide synthase in the hypertrophic cadiocyte of rats suffered abdominal aorta constriction.Objective: To explore the molecular biological mechanism for tanshinoneâ…¡A reversing left ventricular hypertrophy, it would be studying the effect of tashinone on the endothelial nitric oxide synthase( eNOS) in the hypertrophic cadiocyte of rats suffered abdominal aorta constriction.Methods: To detect the nitric oxide content by nitrate reductase, to detect the genic expression of eNOS by RT-PCR and to detect the activity of protein kinase C( PKC) by Western blotting.Results:1. The expressive lever of eNOSmRNA and protein in myocardial hypertrophy group was less than that in other groups(p<0.01). And valsartan group was less than tanshinoneâ…¡A groups and artificial surgery group(p<0.05), but there were no difference among the two tanshinoneâ…¡A groups and artificial surgery group(p>0.05).2. The expression of PKC in myocardial hypertrophy group was much more than that in other groups(p<0.01). valsartan group was less than artificial surgery group and tanshinoneâ…¡A groups(p<0.05), but there were no difference among two tanshinoneâ…¡A groups and artificial surgery group(p>0.05).Conclusion: NO/NOS system in local myocardium had close relationship with the pathological process for myocardial hypertrophy. Tanshinoneâ…¡A could produce the pharmacological action to reverse myocardial hypertrophy by inhibiting the activity of PKC and promoting the genic expression of eNOS in local myocardium and the production of endogenous NO.