摘要目的 观察海水淹溺型兔肺损伤后一氧化氮(NO)的变化及不同剂量地塞米松的干预作用,了解地塞米松对海水淹溺型兔肺损伤的作用.方法 兔经气管注入海水,制备海水淹溺型肺损伤兔模型.将35只健康雄性新西兰大白兔随机分为5组:对照组、海水淹溺组、地塞米松低剂量(0.5 mg/kg)、中剂量(1 mg/kg)、高剂量(5 mg/kg)组.海水淹溺组、地塞米松各剂量组于手术稳定20 min后经气管插管注入配方海水(2 ml/kg),对照组气管切开后注入等量生理盐水,地塞米松各剂量组同时经颈动脉注入不同剂量的地塞米松.注射地塞米松后1、3、6 h取血,测血清NO浓度,并于注射地塞米松6 h后处死动物,迅速取出肺脏,测定肺湿/干重比、肺泡灌洗液(BALF)蛋白含量、肺组织中丙二醛(MDA)含量、一氧化氮合酶(NOS)活性、超氧化物歧化酶(SOD)活性,在光镜下观察肺形态结构的变化.结果 海水淹溺可以使肺湿/干重比、肺泡灌洗液内蛋白含量、血浆中NO含量、肺组织中NOS活性升高,使MDA含量增加、SOD活性降低,引起肺形态结构的病理变化.地塞米松可减轻海水淹溺引起的肺损伤,但地塞米松各剂量组与海水淹溺组之间未见明显差异.结论 海水淹溺可明显升高兔血清中的NO含量,地塞米松可减轻海水淹溺性肺损伤.

abstractsObjective To observe changes of nitric oxide in acute lung injury induced by seawater drowning in rabbits, and to explore effects of-dexamethasone at different doses on acute pulmonary damage. Methods Acute lung injury model was developed with intratracheal instillation of seawater. Thirty -five healthy New Zealand rabbits were randomly divided into 5 groups (n =7, each group): one group with saline treatment, the control group with intratracheal seawater instillation (2 ml/kg)and the rest 3 groups were treated with dexamethasone at different doses (0.5 mg/kg, 1 mg/kg, 5 mg/kg respectively). Sea water was instilled into the lower trachea 20 minutes after surgery. The anesthetized rabbits were given different doses of dexamethasone through injection into cervical artery. Nitric oxide (NO) levels in serum were measured at 1h, 2 h, 3 h and 6 h after injection of dexamethasone. All the animals were sacrificed 6 hours after injection of dexamethasone. The value of W/D, protein content of bronchoalveolar lavage fluid (BALF), levels of malondialdehyde (MDA), activity of nitric oxide synthase (NOS) and superoxide dismutase (SOD) in pulmonary tissues were determined. Changes in orphological structure of lung tissues were observed with light microscopy. Results Seawater drowning could significantly elevate values of W/D, protein contents in BALF and NO levels in serum, enhance MDA and NOS activity and decline SOD activity. Dexamethasone could alleviate acute lung injury induced by seawater drowning. No significant differences in pathological changes were noted between the examethasone treatment group and the seawater drowning group. Conclusions Experiment showed that seawater drowning could significantly increase NO levels in rabbit serum, and dexamethasone could alleviate lung injury induced by seawater drowning, however, no significant statistical differences were seen between the three groups treated with different doses of dexamethasone.