Protective Effect Of Dexmedetomidine Pretreatment On Lung Injury Model Induced By Limb Ischemia-reperfusion In Rats

Background:purpose:To investigate the protective effect of dexmedetomidine?DEX?preco-nditioning on lung injury model induced by limb ischemia-reperfusion in rats.method:A total of 40 healthy male Spragne-Dawley rats were randomly divided into four groups?n=10?:sham operation group?SO group?,D₁₀0 pretreatment group(DEX10ug/kg,D₁₀0 group),D₅₀0 pretreatment group.(DEX50ug/kg,D₅₀0 group),ischemia-reperfusion group?I/R group?,under the light microscope,each group observe the pathological changes of lung tissue?HE staining?.The arterial oxygen partial pressure?PaO₂?,the dry-to-wet weight ratio?W/D?of lung tissue,the degree of oxidative stress injury,the expression of apoptotic factors in lung tissue and the release of inflammat-ory mediators were measured and statistical analysis.result:1.The lung tissue of four groups of rats under light microscope,the alveolar structure of SO group was clear,the matrix was normal,no thickening,no edema,and some inflammatory cells were visible.Compared with the SO group,the alveolar local collapse and atelectasis in the I/R group,the alveolar structure was severely damaged,the vasodilatation was congested,the alveolar septum was thickened,interstitial edema,and it was filled with many neutrophils and macrophages..The alveolar borders of D₁₀0 group and D₅₀0 group were relatively intact,the structure was clearly visible,with a small amount of edema exudation and inflammatory cell infiltration.The pathological changes of lung tissue in D₅₀0 group were significantly better than those in D₁₀0 group.There was no significant difference between D₅₀0 group and SO group?P>0.05?.2.Compare the levels of PaO2 and lung tissue W/D in four groups of experimental rats:a.The comparison results of PaO2 were:SO group>D₅₀0 group>D₁₀group>I/R group,the difference was statistically significant?P<0.05?;b.W/D ratio:SO group<D₅₀0 group<D₁₀0 group<I/R group,the difference was statistically significant?P<0.05?;3.The degree of oxidative stress damage in four groups of experimental rats was compared:a.The results of SOD content comparison were as follows:SO group>D₅₀group>D₁₀0 group>I/R group,the difference was statistically significant?P<0.05?b.The results of MDA content comparison were as follows:SO group<D₅₀0 group<D₁₀group<I/R group,the difference was statistically significant?P<0.05?;4.The comparison results of inflammatory mediators?IL-6,TNF-??in the four experimental rats were as follows:SO group<D₅₀0 group<D₁₀0 group<I/R group,the difference was statistically significant?P<0.05?;5.The levels of apoptotic factors in lung tissue of four groups experimental rats were compared as follows:a.bax?Caspase-3:SO group<D₅₀0 group<D₁₀0 group<I/R group,the difference was statistically significant?P<0.05?;b.bcl-2:SO group>D₅₀group>D₁₀0 group>I/R group,the difference was statistically significant?P<0.05?In conclusion:1.The effects of limb ischemia-reperfusion on lung injury in rats are Obvious.2.Pretreatment with dexmedetomidine can effectively alleviate the ultrastr-uctural damage of lung tissue and improve lung ventilation.It can partially reverse the lung injury induced by limb ischemia-reperfusion in rats in a dose-dependent manner.