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目的 探讨心肌衰老机制。 方法 采用 Wistar大鼠 ,分老龄组 (2 2月龄 )和成年组 (7月龄 )。用透射电镜观察心肌细胞器形态定性改变 ;用体视学方法测定心肌细胞器形态定量改变 ;用 X射线能谱仪分析心肌细胞器调控 Ca2 +能力。 结果 与成年组比较 ,老龄组大鼠心肌改变 :(1)核有切痕、肌原纤维不规整、闰盘离解、线粒体和肌浆网肿胀、脂褐素和残余体增多。(2 )在心肌组织内 ,非肌细胞所占体积份数增加 ,线粒体和肌浆网体密度减少 ,线粒体外膜比面积、内膜 +嵴比面积、肌浆网比面积减少。(3)在舒张状态下 ,肌原纤维和线粒体内 Ca2 +增加 ,肌浆网内 Ca2 +减少。 结论 衰老心肌的舒缩力减退 ,心肌细胞器形态呈明显改变 ,心肌衰老与线粒体和肌浆网的形态改变及其调控 Ca2 +能力有直接关系。
Objective To investigate the mechanism of myocardial aging. Methods Wistar rats were divided into the aging group (22 months old) and the adult group (7 months old). Transmission electron microscopy was used to observe the morphological changes of cardiac organelles. The morphological changes of myocardial organelles were determined by stereological methods. The ability of cardiocytes organelles to regulate Ca2 + was analyzed by X-ray energy dispersive spectroscopy. Results Compared with the adult group, the myocardial changes in the aged rats were: (1) There were incisions in the nucleus, irregular myofibrils, dissociation in the intercalated disc, swelling of mitochondria and sarcoplasmic reticulum, increased lipofuscin and residual body. (2) In myocardial tissue, the proportion of non-muscle cells increased, the density of mitochondria and sarcoplasmic reticulum decreased, the area of mitochondrial outer membrane, the area of intima + crest and the area of sarcoplasmic reticulum decreased. (3) In the diastolic state, Ca2 + increased in myofibrils and mitochondria, while Ca2 + decreased in sarcoplasmic reticulum. CONCLUSION: The decline of the contractile and contractile force and the change of the shape of cardiac organelles in aged myocardium are directly related to the change of morphology of mitochondria and sarcoplasmic reticulum and its regulation of Ca2 +.