应用背向散射积分技术评价糖尿病大鼠心肌纤维化

Study on myocardial fibrosis in diabetes mellitus using ultrasonic integrated backscatter parameters

目的检测不同病程糖尿病模型大鼠的心肌背向散射积分(IBS),同时观察纤维化指标,探讨IBS与心肌纤维化的关系。方法腹腔注射链尿佐菌素(65 mg.kg-1)建立SD大鼠糖尿病模型,于第4、12、24周测定常规心功能参数(LVEF)、左室后壁校正IBS值(IBS%)、IBS周期性变异幅度(CVIB)。同期检测心肌纤维化指标:心肌羟脯氨酸含量(HPC),M asson染色观察胶原纤维容积分数(CVF)及血管周围胶原面积(PVCA),用免疫组织化学法对心肌胶原蛋白在心肌的分布及表达进行半定量分析,光镜与透射电镜对心肌行组织学观察,并与同龄正常大鼠进行比较。结果(1)与对照组比较,糖尿病组的IB%明显增高(P<0.05),CVIB第4、12周时尚无明显变化(P>0.05),第24周时明显降低(P<0.05),LVEF值各组间无明显变化(P>0.05);糖尿病组心肌纤维化指标HPC、CVF、PVCA、胶原蛋白Ⅰ和Ⅲ的表达均明显增高(P<0.05)。(2)IBS%与HPC、CVF、PVCA、胶原蛋白Ⅰ和Ⅲ表达水平呈正相关(P<0.05)。(3)电镜发现糖尿病组心肌细胞肌丝稀疏,线粒体肿胀,间质胶原增生。结论胶原蛋白Ⅰ持续性增加是糖尿病模型鼠心肌纤维化的主要原因。通过监测IBS可以观察糖尿病大鼠心肌组织纤维化的程度。

Objective To investigate the relation between myocardial ultrasonic integrated backscatter （IBS） and myocardial fibrosis of diabetic rats in the different stages. Methods The diabetes mellitus in healthy male Sprague-Dawley rats was induced by a single injection of streptozotocin（ STZ ,Sigma） into intraperitoneal at a dose of 65 mg·kg^-1 body weight. Left ventricular ejection fraction （LVEF）, myocardial calibrated IBS （IBS%）, the cyclic variation of IBS（ CVIB ） by IBS, were determined in the rats of 4,12 and 24 weeks after DM was induced. The myocardial hydroxyproline concentration （ HPC ） was performed. Masson＇ trichrome staining were used in the study of total collagen area. The type Ⅰ and Ⅲcollagen protein expression was evaluated in heart by qualitative and semiquantitative immunohistochemical staining, while the age-matched normal rats served as control group. Myocardiopathological change electron microscope. Results were observed with light microscope and transmission （1） The IBS% of left ventricular posterior wall was significantly higher in diabetic rats than those in the control group（P 〈0.05 ） ,but the CVIB of 24-week diabetic rats was lower（P 〈 0.05 ）. The LVEF had no great alteration in six groups （P 〉 0.05 ）. Compared with the control group, HPC, collagen volume fraction （ CVF）, perivascular collagen area （ PVCA）, and the expression of the typeⅠ and Ⅲcollagen in heart were increased in diabetic rats （ P 〈 0.05 ）. （ 2 ） The correlation between IBS% and HPC, CVF, PVCA, Collagen Ⅰ , Collagen Ⅲ, were significant （ P 〈 0.05 ）. （ 3 ） Myofilament rarefaction, mitrochondrial swelling,interstitial collagen hyperplasia in diabetic rats were observed by electron microscope. Conclusion The increasing collagen Ⅰ proteins are the main cause of myocardial fibrosis in diabetes mellitus. Ultrasonic myocardial IBS have been demonstrated to reflect the degree of myocardial fibrosis in diabetic rats.