Effects of penehyclidine hydrochloride on acute lung injury induced by blunt chest trauma-hemorrhagic shock and resuscitation in rats

Abstract

Objective To investigate the effects of penehyclidine hydrochloride (PHC) on acute lung injury induced by blunt chest trauma-hemorrhagic shock and resuscitation in rats.Methods Forty male SpragueDawley rats,aged 8 weeks,weighing 250-300 g,were randomly assigned into 4 equal groups (n =10 each) using a random number table:sham operation group (S group),blunt chest trauma combined with hemorrhagic shock and resuscitation group (group THSR),PHC for prevention group (group P1)and PHC for treatment group (group P2).ALI was induced by dropping a 300 g weight onto a precordial protective shield to direct the impact force away from the heart and toward the lungs in anesthetized rats in THSR,P1 and P2 groups.Blood was withdrawn via the femoral artery 5 min later until MAP was decreased to 35-45 mmHg within 15 min and maintained at this level for 60 min,followed by resuscitation.In P1 group,PHC 2 mg/kg was injected intravenously at 30 min before blunt chest trauma.In P2 group,PHC 2 mg/kg was injected intravenously at 60 min after hemorrhagic shock.At 6 h after the model was established,arterial blood samples were obtained for blood gas analysis and for measurement of concentrations of interleukin-6 (IL-6) and interleukin-1β (IL-1β) in serum by ELISA.Oxygenation index (OI) was calculated.The animals were sacrificed and bronchoalveolar lavage fluid (BALF) was collected for determination of white blood cell count and protein concentrations.Lungs were removed for examination of pathological changes and ultrastructure and for determination of Toll-like receptor (TLR4) and phosphor-p38 mitogen activated protein kinase (p-p38MAPK) expression (by Western blot).Results Compared with group S,PaO2 and OI were significantly decreased,PaCO2,protein concentrations in BALF,white blood cell count,and IL-6 and IL-1β concentrations in serum were increased,and TLR4 and p-p38MAPK expression was up-regulated in THSR,P1 and P2 groups.Compared with group THSR,PaO2 and OI were significantly increased,PaCO2,protein concentrations in BALF,white blood cell count,and IL-6 and IL-lβ concentrations in serum were decreased,TLR4 and p-p38MAPK expression was down-regulated in P1 and P2 groups.No significant differences were found in the parameters mentioned above between P1 and P2 groups.Conclusion PHC can mitigate acute lung injury induced by blunt chest trauma-hemorrhagic shock and resuscitation in rats,and inhibited activation of TLR4/ p38MAPK signaling pathway and attenuated inflammatory responses are involved in the mechanism. Key words: Cholinergic antagonists; Thoracic injury; Shock, Hemorrhagic; Respiratory distress syndrome, adult