超声背向散射积分评价糖尿病心肌病大鼠左室心肌间质纤维化及缬沙坦的干预效果

Study of the left ventricular myocardial interstitial fibrosis and effect of valsartan in diabetic cardiomyopathy rats by integrated backscatter technique

目的应用超声背向散射积分（IBS）技术评价糖尿病心肌病（DCM）大鼠左室心肌间质纤维化及缬沙坦的治疗效果。方法Wistar大鼠40只、分为对照组（8只）、DCM组（16只）和缬沙坦组（16只），高热量饲料喂养加链脲佐菌素注射制作DCM大鼠模型，成模后缬沙坦组给予缬沙坦（30mg／kg）干预，观察各组大鼠生化指标、血流动力学，电子显微镜、Masson染色检测左室心肌组织胶原含量，超声IBS技术评价各室壁声学密度的变化。结果实验末（血糖升高16周后）与对照组相比，DCM组大鼠心功能明显下降，左室心肌组织胶原含量明显升高（P〈0.05）；血糖升高12周后，与对照组相比，DCM组大鼠左室各壁校正的IBS值（IB％）均明显升高（P〈0．05），左室后壁和室间隔的IBS周期变化幅度（CVIB）明显降低（P〈0．05）；实验末DCM组大鼠左室各壁IB％和CVIB与对照组相比差异均有统计学意义（P〈0．05～0．01）；缬沙坦组大鼠心功能明显好转，心肌间质胶原沉积减轻，IBS参数的异常较DCM组减轻。相关性分析显示，DCM组左室心肌组织胶原含量、左室各壁IB％与空腹血糖均呈明显的正相关（P〈0．05～0．01）；而左室后壁、左室侧壁CVIB与心肌组织胶原含量呈负相关（P〈0．05）。结论DCM存在明显的心肌间质纤维化，缬沙坦可以在一定程度上逆转DCM心肌间质纤维化，超声IBS技术可用于评价DCM大鼠左室心肌间质纤维化的程度。

Objective To assess left ventricular myocardial interstitial fibrosis and effects of valsartan in diabetic cardiomyopathy（DCM） rats by integrated backscatter （IBS） technique. Methods Forty Wistar rats were divided into 3 groups： control group（ n = 8）, DCM group（ n = 16） and valsartan group（ n = 16）. DCM rat models were made by a high-calorie diet and intraperitoneal STZ （30 mg/kg） injection. After that, the valsartan group animals were dosed orally with valsartan （30 mg/kg） every day. The contents of fast blood-glucose, insulin, triglyeeride （TG）, cholesterol （Chol） and insulin sensitivity index （ISI） were analyzed. Hemodynamics indexes were measured. The contents of collagen were quantified by Massonstaining and electron microscopy. The normalized IBS （IB%） and cyclic variation of IBS （CVIB） in left ventricular walls were recorded. Results At the end of the experiment, after 16 weeks hyperglycemia, compared with the indices of the control group, cardiac function of the DCM group decreased（ P〈0. 05）. The content of collagen in the DCM group was higher significantly than that of the control group（ P〈0.05）. After 12 weeks hyperglycemia, compared with the indices of the control group, IB% of the left ventricular walls was increased （ P 〈 0. 05） and CVIB of left ventricular posterior wall （LVPW） and interventricular septa（IVS） was decreased in the DCM group （ P〈0.05）. At the end of the experiment, compared with the indices of the control group, IB% of the left ventricular wails were increased and CVIB of the left ventricular walls was decreased in the DCM group（ P 〈0.05-0.01 ）. The cardiac function of the valsartan group was better and the content of collagen in the valsartan group were lower significantly than those of the DCM group（ P 〈0.05）. After 12 or 16 weeks hyperglycemia, the changes of IB% and CVIB of the left ventricular walls in the valsartan group were lighter than those of the DCM group（ P 〈0. 05）. In the DCM group, there was a significantly positive correlation between the collagen content and the fast blood-glucose（ r = 0. 746, P 〈0.01）, as well as between the collagen content and IB% of LVPW, left ventricular anterior wall（LVAW）, left ventricular lateral walI（LVLW） and IVS（ r = 0. 734, 0. 683, 0. 802, 0. 608, P 〈0.05-0.01）. The collagen content showed a significantly negative correlation with CVIB of LVPW and LVLW（ r = - 0. 634, - 0. 689, P 〈0. 05）. Conclusions The myocardial interstitial fibrosis in DCM is obviously. Valsartan can prevent the damage. It is feasibility to assess left ventricular myocardial interstitial fibrosis in DCM rats by IBS technique.