The studies on the changes of nitric oxide synthase in the lung tissue of traumatic hemorrhagic shock rats under dry heat environment of desert and their relations to the secondary lung injuris / 中华急诊医学杂志

ABSTRACT

Objective To study the pathological changes and expressions of NO and iNOS mRNA in the lung tissue of traumatic hemorrhagic shock rats under dry heat environment of desert and their relations to the lung injury.Methods A total of 140 male SD rats were randomly (random number) ivided into the room temperature (25 ℃) environment traumatic hemorrhagic shock group (room temperature group) and the dry heat traumatic hemorrhagic shock groups (dry heat group,temperature 40℃,humidity 10％),respectively,and each groups was further randomly divided into 7 subgroupsthe control subgroup,post shock subgroups at 0,0.5,1,1.5,2and 3 h (n =10 in each subgroup).The rats of control subgroup were not treated,and rats of dry heat group were placed in dry heat environment for 60 min,then anesthetized,fixed,and insertion of intravenous indwelling needles and catherization of right carotid artery,jugular vein and the right femoral artery were performed.After stabilization for 10 min,2500 g iron wheel was used to be dropped from 30 m height and vertically hit the upper left femoral of SD rats in order to make comminuted fracture,wounds were quickly dressed after injury.Exsanguination from right femoral artery was kept until MAP maintained at (35 ± 5) mmHg,and resuscitation was carried out after continue monitoring for 60 min.After the establishment of traumatic hemorrhagic shock model in each environment,the rats were sacrificed at given intervals,and thoracotomy was performed to take broncho-alveolar lavage fluid (BALF) and lung tissue.Pathological changes of lung tissues were observed by using HE staining and NO concentration of lung tissue was detected by one-step method,and changes of the iNOS mRNA expressions were detected by using fluorescence quantitative PCR.Then t test,ANOVA and Pearson correlation analysis were used for the data analysis.Results The pathological change in dry heat group at each interval was more severe,and pulmonary histopathological injury score was higher,and the protein exudation was more profuse compared with the room temperature group.NO concentration in lung tissue homogenate of dry heat group was higher than that of room temperature group (t =2.472,P ＜ 0.05),and the difference in NO level between different intervals within the dry heat group was statistically significant (F =6.77,P ＜ 0.01).The NO concentration in dry heat group reached its maximum at 2 h (3.35 ± 0.23) μmol / g and the peak value emerged sooner than that in room temperature group.The difference was statistically significant in overall expression of iNOS mRNA between two groups analyzed with t test (t =3.619,P ＜ 0.01),and there was statistically significant difference between intervals within the dry heat group (F =12.34,P ＜0.01).The values of iNOS mRNA in the dry heat group were higher than those in the room temperature group at the same given intervals,and the peak value appears at 1.5 h in dry heat group,and the room temperature group it began to increase at 2 h.The concentration of NO and the expression of iNOS mRNA were positively correlated with each other in two groups (r =0.680,r =0.376).The expression of iNOS mRNA and lung histopathological injury score was positively correlated in two groups (r =0.846,r =0.899).Conclusions When traumatic hemorrhagic shock occurred in the dry heat desert environment,the lung injury was more severe and appeared sooner than that in the room temperature environment.NO and iNOS played important roles in the secondary lung injury in the wake of traumatic hemorrhagic shock in rats under the dry heat environmengt of desert.