| Objective:To investigate the change of?3-adrenergic receptor??3-AR?expression in infarction myocardium and whether the myocardial protective effect of?3-AR is through nitric oxide sythase?NOS?pathway in rats with myocardial infarction?MI?.Methods:1.40 male rats were divided into the following four groups:Sham operated group?Sham group?,MI group,MI+BRL group and MI+SR group.MI model was established by left anterior descending artery ligationy.The rats in the MI+BRL group received selective?3-AR agonist,BRL-37344?4.0 nmol/kg/min,10 min,3times per week for 3 weeks?via tail vein injection.The rats in the MI+SR group received selective?3-AR antagonist,SR59230A?0.56 mg/kg/min,10 min,3 times per week for 3 weeks?.The rats in the Sham group and MI group received nomal saline?4.0 nmol/kg/min,10 min,3 times per week for 3 weeks?via tail vein injection.2.Echocardiography was performed to measure left ventricular ejection fraction?LVEF?,left ventricular end-diastolic diameter?LVEDD?and left ventricular end-systolic diameter?LVESD?.3.Masson's trichrome staining was performed to observe fibrosis in infarction myocardium.Myocardial apptosis was detected by terminal deoxynucleltidyl transferase mediated dUTP nick-end labeling?TUNEL?.4.The expression of?3-AR mRNA,endothelial NOS?eNOS?mRNA,neuronal NOS?nNOS?mRNA in the infarction myocardium were detected by quantitative real-time polymerase chain reaction?RT-qPCR?.Results:1.Echocardiography parameters?1?Compared with the Sham group,left ventricular ejection fraction?LVEF?was significant lower?P<0.05?,the LVEDD and LVESD were significant larger?P<0.05?in the MI group were larger than Sham group.?2?Compared with the MI group,the LVEF was significant larger?P<0.05?,the LVEDD and LVESD were significant lower?P<0.05?in the MI+BRL group were lower than MI group.?3?Compared with the MI+BRL group,the LVEF was significant lower?P<0.05?,the LVEDD and LVESD were significant larger?P<0.05?in the MI+SR group were larger than MI+BRL group.2.The result of Masson's trichrome staining?1?The pathological changes of myocardial fibrosis were more obvious in the MI group than that in the Sham group.?2?The pathological changes of myocardial fibrosis were more descend in the MI+BRL group than that in the MI group.?3?The pathological changes of myocardial fibrosis were more obvious in the MI+SR group than that in the MI+BRL group.3.The results of TUNEL?1?The pathological changes of myocardial apoptosis were more obvious in the MI group than that in the Sham group?P<0.05?.?2?The pathological changes of myocardial apoptosis were more descend in the MI+BRLgroup than that in the MI group?P<0.05?.?3?The pathological changes of myocardial apoptosis were more obvious in the MI+SR group than that in the MI+BRL group?P<0.05?.4.The results of RT-qPCR4.1?3-AR mRNA expression?1?The level of?3-AR expression in the infarction myocardium in the the MI group was significantly higher than in the Sham group?P<0.05?.?2?The level of?3-AR expression in the infarction myocardium in the the MI+BRL group was significantly higher than in the MI group?P<0.05?.?3?The level of?3-AR mRNA expression in the infarction myocardium in the MI+SR group was obviously lower than MI+BRL group?P<0.05?.4.2 eNOS mRNA expression?1?The level of eNOS mRNA expression in the infarction myocardium in the MI group was obviously lower than Sham group?P<0.05?.?2?The level of eNOS mRNA expression in the infarction myocardium in the MI+BRL group was obviously higher than MI group?P<0.05?.?3?The levels of eNOS mRNA expression in the infarction myocardium in the MI+SR group was obviously lower than MI+BRL group?P<0.05?.4.3 nNOS mRNA expression?1?The level of nNOS mRNA expression in the infarction myocardium in the MI group was obviously lower than Sham group?P<0.05?.?2?The level of nNOS mRNA expression in the infarction myocardium in the MI+BRL group was obviously higher than MI group?P<0.05?.?3?The level of nNOS mRNA expression in the infarction myocardium in the MI+SR group was obviously lower than MI+BRL group?P<0.05?.4.4The relationship between?3-AR mRNA expression and NOS mRNA expression?1?In all animals,there was a positive correlation between the level of?3-AR mRNA expression and eNOS expression?r=0.219,P=0.008?.?2??3-AR mRNA expression also positively correlated with nNOS expression ?r=0.237,P=0.004?.Conclusions:1.The expression of?3-AR mRNA was upregulated in infarction myocardium in the rats with myocardial infarction.2.The myocardial protective effect of?3-AR maybe is through NOS pathway in rats with myocardial infarction. |
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