Effect of BML-111 on acute lung injury induced by hemorrhagic shock and resuscitation in rats

Objective To evaluate the effect of lipoxin A4 receptor agonist BML-111 on acute lung injury induced by hemorrhagic shock and resuscitation in rats.Methods Thirty-two healthy male Sprague-Dawley rats,aged 6-8 weeks,weighing 200-250 g,were randomized into 4 groups (n =8 each) using a random number table:sham operation group (S group),hemorrhagic shock/resuscitation group (HSR group),BML-111 group,and BML-111 plus BOC-2 (lipoxin A4 receptor antagonist) group (BOC-2 group).The animals were anesthetized with 2％ pentobarbital sodium 80 mg/kg,tracheostomized and mechanically ventilated.Left common carotid artery was cannulated for blood-letting and fluid infusion.Hemorrhagic shock was induced according to the method described by Kochanek et al.MAP was reduced to 35-45 mmHg and maintained at this level for 30 min.The animals were then resuscitated for 30 min with infusion of the blood withdrawn and lactated Ringer' s solution 2 times the volume of blood withdrawn.In BML-111 and BOC-2 groups,BML-111 (1 mg/kg) was injected intraperitoneally at the beginning of resuscitation.In BOC-2 group,BOC-2 (50 μg/kg) was injected intraperitoneally before blood-letting.The rats were sacrificed at 2 h after completion of resuscitation.Bronchoalveolar lavage fluid (BALF) was collected for determination of neutrophil count.Lungs were excised for microscopic examination of the pathological changes and for determination of wet/dry lung weight ratio (W/D ratio),contents of interleukin-1 (IL-1β) and IL-6,and phosphorylation of mitogen-activated protein kinase (MAPK).Results Compared with group S,the neutrophil count in BALF,W/D ratio,contents of IL-1β and IL-6,and phosphorylation of MAPK were significantly increased in HSR group (P ＜ 0.05).The neutrophil count in BALF,W/D ratio,contents of IL-1β and IL-6,and phosphorylation of MAPK were significantly lower in BML-111 group than in HSR group,and higher in BOC-2 group than in BML-111 group (P ＜ 0.05).Conclusion BML-111 can attenuate acute lung injury induced by hemorrhagic shock and resuscitation in rats and inhibition of activation of MAPK pathways and reduction of inflammatory responses in lung tissues are involved in the mechanism. Key words: Receptors, lipoxin ;  Shock, hemorrhagic ;  Respiratory distress syndrome, adult