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目的探讨心肌肥厚大鼠背向散射积分的变化情况,并结合心肌细胞外基质的病理改变及其重要影响因子基质金属蛋白酶(MMP-9)和其生理性抑制剂(TIMP-1)在蛋白和基因水平的表达,探讨其相互关系。方法SD大鼠腹腔注射去甲肾上腺素[1.06 mg/(kg·d)×15 d]建立心肌肥厚的动物模型,测定室间隔中部心肌的背向散射参数,并应用免疫组化和逆转录一聚合酶链反应法(RT-PCR)方法检测心肌总体胶原、Ⅰ型和Ⅲ型胶原的改变,及MMP-9,TIMP-1蛋白和mRNA的表达,与超声测定的结果进行对比研究。结果(1)实验组大鼠心肌胶原成份及MMP-9,TIMP-1的表达显著高于健康对照组(P<0.01)。(2)超声背向散射积分(IBS%)在实验组较对照组高(P<0.01),与心肌胶原、MMP-9和TIMP-1的表达之间存在相关性。结论大鼠心肌肥厚时IBS%升高与胶原的过渡沉积密切相关,而MMP-9和TIMP-1可能是引起心肌细胞外基质重塑的重要机制之一。
Objective To investigate the changes of backscatter integral in cardiac hypertrophy rats and to explore the relationship between the changes of myocardial extracellular matrix and the important factors MMP-9 and its physiological inhibitor TIMP-1 in protein and Gene expression, to explore the relationship between them. Methods SD rats were intraperitoneally injected with norepinephrine [1.06 mg / (kg · d) × 15 d] to establish an animal model of cardiac hypertrophy. The backscattering parameters of the midtrochanteric myocardium were measured and compared with immunohistochemistry and reverse transcriptase-1 Polymerase chain reaction (RT-PCR) was used to detect the change of total collagen, type I and type III collagen, and the expression of MMP-9, TIMP-1 protein and mRNA, and compared with the results of ultrasound. Results (1) The expression of myocardial collagen and MMP-9, TIMP-1 in experimental group was significantly higher than that in healthy control group (P <0.01). (2) Ultrasound backscatter integral (IBS%) was higher in the experimental group than in the control group (P <0.01), and there was a correlation between the expression of myocardial collagen, MMP-9 and TIMP-1. Conclusions The elevated IBS% of myocardial hypertrophy in rats is closely related to the transitional deposition of collagen, while MMP-9 and TIMP-1 may be one of the important mechanisms that cause extracellular matrix remodeling.