Effects Of Resuscitation With 100% Oxygen Or Room Air On Pulmonary Alveolus Of Asphyxia Neonatal Rat

[Objective]To compare the effect of pure oxygen and air resuscitation on the damage of alveoli and the expression of Bcl-2 and Bax protein of asphyxia neonatal rats.[Methods]Thirty neonatal rats were randomly divided into three groups:the control group, the room air group and the pure oxygen group.Models of hypoxia rats were established,right lung tissues were taken at 24^th h and 72^th h of the experiment.The specimen for electron microscopic and light microscopic examination were prepared by routine techniques.The apoptosis index(AI) OF alveolar tissue was achieved by terminal deoxynucletoidy transferase-mediated d-UTP nick end labeling(TUNEL). The expression of Bcl-2,Bax in alveolar tissue was evaluated by quantitative immunohistochemistry.Morphological and ultrastructural changes of alveloar tissue were observed by light microscopy and transmission electron microscopy respectively.[Results]1.The reduced number of pulmonary alveoli,thickened alveolar septum,congestion of microvessels and inflammatory cell infiltration were found in both PO and RA group by using light microscope.Flocky substance in the alveolar spaces and formation of pneumatocele were found in PO group.There was no marked differences between the 24h and 72h sub-groups in both PO group and RA group.2.Pathological ultrastructurally changes could be showed in both RA and PO group:alveolar epithelial cellⅠ(AECⅠ) was partly swollen,cytoplasm fell off, mitochondria were swollen and lamellar bodies in the alveolar epithelial cellⅡ(AECⅡ) lost their normal structure and reduced in number and microvilli were rare.In the RA group,the above mentioned changes were somewhat mild as compared with PO group.Comparing 24^th h and 72^th h subgroup of RA group and PO group respectively,no significant difference could be seen.3.Compared with the control group,the expression of Bcl-2,Bax,ratio of Bcl-2/Bax and AI of pulmonary alveolar cell in PO group and RA group were obviously increased(P＜0.05).Above-mentioned indexes were significantly different between PO group and RA group(P＜0.05).Compared with 24h sub-group in each group,the expression of Bcl-2 was increased,the expression of Bax was decreased,the ratio of Bcl-2/Bax all showed a rising tendency in the 72h sub-group(P＜0.05);AI of pulmonary alveolar cell had no significant change between 24h sub-group and 72h sub-group in each group(P＞0.05).[Conclusion]1.Resuscitation with 100%oxygen induced obvious impairment to the neonatal rat lung by apoptosis;the high expression of Bcl-2 and Bax might play an important role in the development of impairment;inversely resuscitation with room air cause much milder impairment,compared to the PO group,which might be related to the up-regulation of Bcl-2/Bax.2.Using high-concentration oxygen for resuscitating asphyxia newborn should be careful.