高血压大鼠左心室肥大心肌细胞中Src激酶膜转位的研究

Membrane translocation of Src kinase in cardiac myocytes of hypertrophic left ventricle of hypertensive rats

目的:探讨Src激酶在高血压所致左心室肥大发病机制中的作用。方法:以自发性高血压大白鼠(SHR)为研究对象,通过免疫荧光标记、共聚焦显微镜观察及蛋白质印迹等方法,检测不同月龄的SHR左心室肥大心肌细胞中Src激酶的表达和定位的变化。结果:蛋白质印迹检测显示,Src激酶在2、6、12和18月龄的SHR组左心室心肌组织抽提的总蛋白匀浆中的表达量与相同月龄的对照Wistar-kyoto(WKY)大鼠组相比较,无明显变化;而在其抽提的胞质蛋白匀浆中和膜蛋白匀浆中,2月龄的SHR组与对照WKY大鼠组相比较,Src激酶的表达无明显差别,但将6、12、18月龄的SHR组分别与相同月龄的WKY大鼠组比较,在胞质蛋白匀浆中Src激酶的表达显著减少(P<0.05),在膜蛋白匀浆中Src的表达则显著增加(P<0.05)。免疫荧光标记也显示,在6、12和18月龄的SHR心肌细胞中出现一些定位变化,主要表现为Src激酶在心肌细胞闰盘的聚集,在心肌细胞闰盘处可观察到较宽的明亮荧光带,这些变化正好与SHR左心室肥大心肌细胞失代偿性重构相吻合。结论:研究结果表明,在高血压所致失代偿性心肌肥大形成和发展的全过程中,存在Src激酶的膜转位,提示心肌细胞中Src激酶信号转导通路可能参与了高血压所致失代偿性左心室肥大的心肌重构过程。

AIM： To investigate the role of Src in the pathogenesis of left ventricular hypertrophy resulting from pressure load. METHODS ： Expressions and subcellular location of Src were determined using immunofluorescent labeling, confocal microscopy and Western blotting in cardiac myocytes of hypertrophic left ventricle from 2-, 6-, 12-, and 18-month-old spontaneously hypertensive rats （SHR） and age-matched Wistar-Kyoto （WKY） control rats. RESULTS： No significant difference was seen in Src expression in the left ventricle tissue homogenate including total protein among 2-, 6-, 12- and 18-month-old SHR and age-matched WKY rats, and no significant difference was observed in the cytoplasmic fraction and membrane fraction between 2-month-old SHR and WKY rats. The expression of Src significantly decreased in cytoplasmic fraction from 6-, 12- and 18-month-old SHR, whereas expression of Src significantly increased in the membrane fraction from 6-, 12- and 18-month-old SHR as compared with those in agematched WKY rats. Confocal microscopy confirmed that as more Src accumulated, more wide fluorescent bands were observed in the intercalated disks of cardiac myocytes from 6-, 12- and 18-month-old SHR compared with what was observed in age-matched WKY control rats. CONCLUSIONS： Subcellular redistribution of Src in the hypertrophic left ventricle of SHR indicates that Src kinase signal transduction pathway may play a critical role in myocardial remodeling in decompensated hypertensive ventricular hypertrophy.