中海拔地区慢性暴露大鼠心肌及肝脏的光镜及电镜观察

A Light and Electron Microscopic Observation of Myocardium and Liver from Rats Chronically Exposed to a Moderate High Altitude

目的 探讨中度海拔高度地区慢性低氧大鼠心肌、肝的组织学及超微结构变化。方法 本实验用Wistar大鼠20只，雌雄各半，六日内从海拔5米运至海拔3418米饲养，8周后断头处死大鼠，留取心肝组织作光电镜观察，同时高原暴露前后测定血RBC数及Hb含量。结果 心肝组织学改变主要为细胞水肿，即心肌颗粒变性，肝细胞疏松化，其次为心肌、肝细胞嗜酸性变。心肌组织有少量小灶状坏死，肝组织中未见坏死。超微结构主要有肌浆网扩张，线粒体肿胀，糖元颗粒减少，未见不可逆性损伤如线粒体出现杆状嵴、三膜嵴及核染色质边聚现象。毛细血管内皮细胞多有突起伸向管腔，胞质空泡变性，微饮泡较少。另外，高原暴露后RBC数及Hb含量明显升高。结论 该海拔地区慢性低氧大鼠心肌、肝组织及毛细血管的病变是可逆性的; 左右心室病变程度无显著性差异; 肝组织的病变程度明显轻于心肌组织。

Objective To investigate histological and ultrastructural changes in myocardium and liver from rats chronically exposed to an altitude of 3 418 m. Methods 20 Wistar rats (male and female each half) were transported to the altitude from an area of 5m above sea level within 6 days. 8 weeks later, the heart and liver tissues of the rats were got and observed under light and electron microscope and the number of RBC and concentration of Hb measured before and after exposure to the altitude. Results The main histological changes in cardiac and liver tissues were cell swelling ,that is, myocardial granular degeneration and liver hydrophobic change. Other lesions were myocytoplasm condensation, liver acidophilic degeneration and small necrotic foci within myocardial fiber, without necroses observed in liver tissue. The main ultrastructural changes included dilation of myoplasmic reticulum, swelling of mitochondria and a decrease in glucogen granule. No irreversible damage was observed such as mitochondria with bar-like,three-membrane or high-density-membrane crista and margination of chromatin. There were protrusions extending to capillary cavity from endothelial cells which also had cytoplasmic swelling and fewer pinosome. In addition, the number of RBC and concentration of Hb increased significantly. Conclusions Myocardial and liver alterations of the rats exposed to a high altitude (3 418 m) for 8 weeks were reversible. Left ventricle alteration was not significantly different from that of the right, and the liver lesions were less severe than those in myocardium.