低氧对大鼠放射性心肌损伤防护作用的早期实验结果

PROTECTIVE EFFECT OF RADIATION- INDUCED RAT’S HEART INJURY UNDER HYPOXIA:The resuLt of preliminary study

用Ｗｉｓｔｅｒ大鼠观察低氧对心肌放射性损伤的防护作用，动物分成空白对照组，单纯照射组和低氧照射组。用４ＭｅＶＸ线照射，剂量为４５０ｃＧｙ×９次／２１天，低氧组在照射前吸入１０．５％的低氧混合气体。照射结束后第７天取活体心脏，进行光镜全心大切片及电镜标本制作。光镜观察未见肌原纤维的变性坏死。３组超微结构统计分析结果表明：线粒体空泡变、胞质水肿、毛细血管的严重损伤出现的频次率低氧组均低于单照组；润盘“脱焊”、肌纤维灶性变性坏死只见于单照组。总体超微结构各级改变出现的频次率，低氧组和单照组无一次正常结构出现，Ⅱ级轻度损伤出现的频次率分别为对照组４３．８％，低氧组８５％，单照组４２％；Ⅲ级中度损伤出现的频次率分别为６．３％、１５％和５４％；Ⅳ级严重损伤只见于单照组。说明低氧降低了心肌放射损伤的程度，起到了一定的保护作用。

AbstractSixty male and femalo mature wister rats were chosen for this study. These rats were dividedinto three groups:control,radiation only and hypoxic radiation in which the rats inhaled 10.5%O_2gas mixture three minutes before irradiation to the end of radiation,Each rat was anesthetized by1%pentobarbital sodium with the rat lying on back,2 × 6cm￣2 radiation field over the heart, andpart of the lung. 4Mev X-ray with 450cGy per fraction Q.O.D.×9 times/21days was given. Eachirradiation was completed within five minutes.Thirty rats were sacrificed on the seventh dav aftl3rthe end of irradiation. The rats' hearts in each group were studied by lightmicroscopy and also byelectron-microscopy,Electron-microphotographs were described with unified standard.Accordingto the mean scoring of every ultrastructure, we scaled the ultrastructural grade of each photo.Conspicuous myocardia degeneration was not seen by lightmicroscopy. Frequency of severedamage(Ⅲgrade)was6.3% in the control;25%in hypoxic radiation and 58.3%in radiation only.The most severe damage(Ⅳ grade)was seen in the radiation only group. The result indicates that10.5%O_2 hypoxic mixture can reduce the radiation damage in rat’s heart.