分层斑点追踪成像评估小鼠生理性老化模型的心肌力学改变

Layer-specific speckle tracking echocardiography in evaluating alterations of myocardial mechanics in mice models of physiological agin

目的探讨小鼠生理性老化过程中心肌内外膜力学参数的改变。方法选择月龄从3周到24月的C57BL/6的小鼠50只,常规超声和分层斑点追踪技术(LS-STE)评估不同月龄(每组10只)小鼠的心肌力学改变;应用HE和Masson三色法评估小鼠生理性老化过程中的心肌病理学改变。结果不同月龄小鼠常规超声所测参数表现为明显的增龄性改变(均P<0.05);LS-STE所测指标提示在生理性老化过程中,小鼠左室径向应变及内膜下、外膜下纵向应变、环向应变值逐渐减低(均P<0.05);与3周组相比,14月龄组小鼠的内膜下纵向应变值显著减低[(-23.49±2.32)比(-17.19±2.28),P<0.05];与3周组相比,24月龄组小鼠的径向应变值[(32.90±5.01)比(21.80±5.54)]、内膜下纵向应变值[(23.49±2.32)比(-15.44±2.27)]、外膜下纵向应变值[(13.23±3.19)比(7.59±2.21)]、内膜下环向应变值[(-25.93±4.09)比(—20.31±4.08)]和外膜下环向应变值[(-9.30±1.92)比(-6.01±1.04)]减低(均P<0.05)。HE及Masson三色法提示老化过程中小鼠心肌组织光镜下表现为心肌横截面积增大,纤维组织增生。结论LS-STE可以精确地评估小鼠模型老化过程中的心功能变化及心肌病理学改变,为评估抗心肌老化提供了新的工具。

ObjectiveTo explore alterations of myocardial mechanics in mice models of physiological aging.MethodsMice aged from 3weeks to 24months were chosen(n=50).Conventional echocardiography and layer speckle tracking echocardiography(LS-STE)were applied to evaluate alterations of myocardial mechanics in different ages(each for 10mise).Pathological myocardial alterations in the aging process were detected using HE and Masson's trichrome staining.Results Clear age-dependent changes in mice of different ages were observed when assessed using parameters of conventional echocardiography(P<o.05 for all).Values from parameters of LS-STE also showed that longitudinal,circumferential and radial strain in both the endocardium and the epicardium gradually decreased during physiological aging(P<0.05 for all).Compared with the 3-weeks old group,longitudinal strain in the endocardium was significantly reduced in the 14-months old group[(-23.49±2.32)us.(-17.19±2.28),P<0.05];Compared with the 3-weeks old group,radial strain,longitudinal strain in the endocardium,longitudinal strain in the epicardium,circumferential strain in the endocardium and circumferential strain in the epicardium were significantly reduced in the 24-months old group[(32.90± 5.01)us.(21.80 ± 5.54),(23.49±2.32)vs.(15.44±2.27),(13.23±3.19)ws.(7.59±2.21),(25.93±4.09)ws.(20.31±4.08),(-9.30±1.92) us.(-6.01±1.04),P<0.05)];HE and Masson's trichrome staining of themyocardium indicated increases in the cross-sectional area of cardiomyocytes and fibrosis during theaging process.Conclusions LS-STE can accurately detect early cardiac dysfunction and pathologicalmyocardial alterations associated with aging in mice and may serve as an effective tool in evaluatinganti-myocardial aging.