Effect of dexmedetomidine on lung injury induced by renal ischemia/reperfusion in rats

Objective To evaluate the effect of dexmedetomidine on lung injury induced by renal ischemia/reperfusion (l/R) in rats.Methods Healthy male Sprague-Dawley rats,aged 4-5 months,weighing 250-300 g,were randomized into 4 groups (n =10 each) using a random number table:sham operation group (group S); group I/R; dexmedetomidine pretreatment group (group D1) and dexmedetomidine postconditioning group (group D2).Renal I/R was induced by right nephrectomy and occlusion of the left kidney for 45 min followed by reperfusion in animals anesthetized with intraperitoneal chloral hydrate.In group D1,dexmedetomidine was infused intravenously starting from 30 min before ischemia until beginning of ischemia.In group D2,starting from onset of reperfusion until 30 min of reperfusion,dexmedetomidine was infused intravenously for 10 min at a rate of 1 μg· kg-1 · h-1,and then infused for 20 min at 0.5 μg· kg-1 · h 1.Blood samples were collected at 6 h of reperfusion to determine serum creatinine,blood urea nitrogen,interleukin-1β (IL-1β),IL-6 and tumor necrosis factor-α (TNF-α) concentrations,and IL-1β,IL-6 and TNF-α concentrations in broncho-alveolar lavage fluid (BALF).Lungs were removed for microscopic examination and for determination of wet/dry lung weight ratio.Results Compared with group S,wet/dry lung weight ratio,serum creatinine and blood urea nitrogen concentrations,and IL-1β,TNF-α and IL-6 concentrations in serum and BALF were significantly increased in the other three groups (P ＜ 0.05).The parameters mentioned above were significantly lower in D1 and D2 groups than in I/R group (P ＜ 0.05).Microscopic examination showed that the pathological changes were significantly attenuated in D1 and D2 groups as compared with I/R group.Conclusion Both dexmedetomidine pretreatment and postconditioning can attenuate lung injury induced by renal I/R and inhibition of inflammatory responses is involved in the mechanism. Key words: Dexmedetomidine;  Respiratory distress syndrome, adult;  Kidney;  Reperfusion injury