Research On Protective Effect Of N-Nitro-L-Arginine In Lungs Of Rats With Smoke Inhalation Injury

Objective:Rats with smoke inhalation injury were the object of this experiment, inject intraperitoneal of L-NNA of different doses and different time length, observed the therapeutic effect of L-NNA in order to identify and to evaluate the protective effect of L-NNA on lungs of rats with smoke inhalation injury.Methods:60rats were randomly divided into4groups,6in blank group, the remaining rats were divided into control group, low dose group and high dose group, and each group set6h,24h,48h three time points,6rats in each time point. The rats without any treatment were put in blank group, the remaining three groups of rats were making models of smoke inhalation injury. Control group, low dose group and high dose group after injury were injected with equivalent saline, the concentration of10mg/kg L-NNA and the concentration of20mg/kg L-NNA. Each rat took blood5ml at the time points mentioned above, centrifuged and tested interleukin6(IL-6), interleukin-10(IL-10), tumor necrosis factor α(TNF-α) content in serum, and tested malondialdehyde (MDA), myeloperoxidase (MPO) and superoxide dismutase (SOD) content in left lung tissue homogenates. A portion of the right lung fixed in4%formaldehyde solution and HE stained pathological, examined the lung tissue under microscope.Results:TNF-α, IL-6content of Low-dose group24h,48h and high-dose group6h,24h,48h significantly decreased compared with control group (P<0.01), MDA, MPO content of low-dose group6h and high dose group6h,24h,48h significantly decreased compared with control group (P<0.01), IL-10, SOD content of the high-dose group6h,24h,48h significantly increased (P<0.01).IL-6, TNF-α, MDA, MPO content of the high-dose group6h,24h,48h was significantly lower than the same time point low-dose group (P<0.01), IL-10,SOD content compared with same time point low-dose group was significantly increased(P<0.01).Rat lung coefficient of control group6h,24h,48h were significantly increased compared with the control group (P<0.01); lung coefficient of low-dose group rats6h,24h,48h and high dose group6h,24h,48h at the same time points decreased significantly than the control group rats (P<0.01), lung coefficient of rats in the high-dose group were significantly decreased compared with the rats of low-dose group at the same time points (P <0.01),Pathological section display that there were fewer inflammatory cell and slightly reduced alveolar collapse in lung tissue of rat in low dose group6h and high dose group6h compared with control group6h, and lung interstitial and alveolar leakage reduced in high dose group than that in the low dose group.Conclusions:N ω-nitro-L-arginine (L-NNA) can reduce inflammation and Peroxidation reaction in the lung tissue of rats with smoke inhalation injury, so as to reduce the degree of lung injury, and protection effect of lung of the rats in high-dose group is better than the low-dose group.