OBJECTIVETo investigate the effects of penehyclidine hydrochloride on apoptosis of lung tissue cells and its mechanism in acute lung injury following blunt chest trauma in rats.

METHODSSprague Dawley (SD) rats (n equal to 54) weighing (250+/-5) g were divided equally and randomly into three groups: normal control group (C group, n equal to 18), trauma model group (T group, n equal to 18) and penehyclidine hydrochloride treatment group (P group, n equal to 18). Each group was further divided into three subgroups according to the time points of 3, 12 and 24 hours after experiment (at each time point, n equal to 6 for each subgroup). Rats of P group were intraperitoneally injected with penehyclidine hydrochloride for 2 mg/kg immediately after blunt chest trauma and rats in its 24 hours subgroup were once again injected with penehyclidine hydrochloride in the same dose 12 hours after injury. Lung tissue samples were collected at every time point and cell apoptosis in lung tissues were measured by TUNEL. Apoptotic index (AI) was calculated, expressions of bax and bcl-2 were detected by immunohistochemical staining of SABC, and lung tissue sections were taken for light and electron microscopic observation.

RESULTSAs compared with C group, at every time point, AI and expressions of bax and bcl-2 in T group were higher (P less than 0.05), and the ratio of bcl-2/bax markedly decreased (P less than 0.05), especially in the 24 hours subgroup. The ratio in T group (0.468+/-0.007) was lower than that in C group (1.382+/-0.058, t equal to 12.5, P less than 0.01). Lung tissue injuries were significant under a light microscope, and the number of apoptotic cells increased obviously under a transmission electron microscope. As compared with T group at the same phase, AI and expression of bax decreased in P group (P less than 0.05 and P less than 0.01), while the expression of bcl-2 increased significantly (P less than 0.01), and the ratio of bcl-2/bax markedly increased (P less than 0.05), especially in the 24 hours subgroup. The ratio in P group (1.012+/-0.070) was much higher than that in T group (0.468+/-0.007, t equal to 8.3, P less than 0.01). The injury of lung tissues was relieved, and apoptosis of cells decreased obviously under a transmission electron microscopic observation.

CONCLUSIONSApoptosis and expressions of bax and bcl-2 in lung tissues might be involved in the pathogenesis of lung injury induced by blunt chest trauma. Penehyclidine hydrochloride can alleviate lung injuries by inhibiting apoptosis of lung tissue cells, during which effects of penehyclidine hydrochloride on regulating expressions of bax and bcl-2 may play an important role.