目的　观察吸入一氧化氮对放射性间质性肺炎的防治效果 ,以期探索防治放射性肺炎的新措施。方法　建立放射性肺纤维化动物模型 ,分别在照前 1d(B和C组 )及照后 1个月 (D和E组 )开始吸入NO ,每种方式均持续治疗 1个月 ,NO吸入浓度为 2 0× 10 - 6 (B和D组 )和 10× 10 - 6 (C和E组 )两个剂量 ,单纯照射组 (A组 )和正常对照组 (F组 )不加任何处理。分别于照射后 1d、1周、1个月、3个月和 6个月取材观察。结果　动物死亡率B组 (10 % )和C组 (5 % )低于其他各组 ;照射后1个月 ,肺重与体重之比B组和C组低于A组 (P <0 0 5 ) ;照后 6个月 ,A组呈现局灶性纤维化 ;B和C组主要在肺叶顶部可见局灶性增生和轻度纤维化病变 ;D和E组可见有较大面积的增生灶 ,主要集中在肺叶顶部。结论　照射前吸入NO明显减轻放射性急性间质肺炎的发生及其病变程度 ,降低动物死亡率 ,延缓和减轻肺纤维化发生的时间和程度 ,而照射后吸入NO此种作用较弱 Objective To observe the effect of inhaled nitric oxide on the prevention and treatment of radiation-induced interstitial pneumonia, in order to explore new measures to prevent and treat radiation pneumonitis. Methods The animal model of radiation-induced pulmonary fibrosis was established. NO was inhaled on the first day before irradiation (groups B and C) and one month after irradiation (groups D and E), and each mode was treated for one month. The NO concentration There was no significant difference between the two groups (group B and D) and the group of 10 × 10 - 6 (group C and E), the group of irradiation alone (group A) and the group of normal control (group F). After 1 d, 1 week, 1 month, 3 months and 6 months after irradiation, the specimens were observed. Results The mortality rate of animals in group B was lower than that in group B (10%) and group C (5%). The ratio of lung weight to body weight in group B and C was lower than that in group A at 1 month after irradiation (P <0.05 ); At 6 months after irradiation, group A showed focal fibrosis; group B and C showed focal hyperplasia and mild fibrosis mainly at the top of lobes; group D and E showed a large area of ​​hyperplasia, Mainly in the top of the lobe. Conclusions The inhalation of NO before irradiation can significantly reduce the incidence of acute interstitial pneumonitis and the extent of its lesion, reduce animal mortality, delay and reduce the time and extent of pulmonary fibrosis, while the effect of NO inhalation after irradiation is weak