Atrial natriuretic peptide attenuates inflammatory responses on oleic acid-induced acute lung injury model in rats

Background An inflammatory response leading to organ dysfunction and failure continues to be a major problem after injury in many clinical conditions such as sepsis,severe burns,and trauma.It is increasingly recognized that atrial natriuretic peptide（ANP） possesses a broad range of biological activities,including effects on endothelial function and inflammation.A recent study has revealed that ANP exerts anti-inflammatory effects.In this study we tested the effects of human ANP（hANP） on lung injury in a model of oleic acid（OA）-induced acute lung injury（ALI） in rats.Methods Rats were randomly assigned to three groups（n=6 in each group）.Rats in the control group received a 0.9%solution of NaCI(1 ml·kg;h;) by continuous intravenous infusion,after 30 minutes a 0.9%solution of NaCI（1 ml/kg） was injected intravenously,and then the 0.9%NaCI infusion was restarted.Rats in the ALI group received a 0.9%NaCI solution(1 ml·kg;h;) intravenous infusion,after 30 minutes OA was injected intravenously（0.1 ml/kg）,and then the0.9%NaCI infusion was restarted.Rats in the hANP-treated ALI group received a hANP(0.1 μg·kg;min;) infusion,after30 minutes OA was injected intravenously（0.1 ml/kg）,and then the hANP infusion was restarted.The anti-inflammation effects of hANP were evaluated by histological examination and determination of serum cytokine levels.Results Serum interleukin（IL）-1β,IL-6,IL-10 and tumor necrosis factor（TNF） a were increased in the ALI group at six hours.The levels of all factors were significantly lower in the hANP treated rats（P<0.005）.Similarly,levels of IL-1β,IL-6,IL-10 and TNF-α were higher in the lung tissue in the ALI group at six hours.hANP treatment significantly reduced the levels of these factors in the lungs（P <0.005）.Histological examination revealed marked reduction in interstitial congestion,edema,and inflammation.Conclusion hANP can attenuate inflammation in an OA-induced lung injury in rat model.