Protective Role Of Carbon Monoxide To Lung And Liver Tissues During Septic Shock Of Rats And Its Primarily Mechanisms

Objective: Endotoxin distribute widely in cell wall of Gram-negative bacterium and other microorganisms.When those microbes die or multiply fast,they can release endotoxin.If a large amount of endotoxin goes into body circulation,endotoxiemia(ETM) and septic shock(SS)will be induced.SS is a common and severe pathological process with high mortality in clinical practice, which can induce disseminated intravascular coagulation(DIC) and multiple organ dysfunction syndrome(MODS).Lung and liver are target organs primarily impaired in the early stage of SS, which can induce acute lung injury(ALI)and acute liver injury. Previous studies demonstrated that ALI was induced by activated leukocytes and the aggregation of inflammatory substances. The mechanism of acute liver injury was similar to ALIand also induced by activated hepatic kuffer cells , which could release many toxic mediators such as the tumor necrosis factor(TNF), interleukin-1(IL-1),interleukin6(IL-6) and so on. Those substances could aggravate the degree of acute liver injury and induce more severe conditions.So how to prevent and cure ALI as well as acute liver injury is the focus of clinical studies.Rencently,carbon monoxide(CO) is being recognized, which is one of the metabolic products of degradation of heme by heme oxygenase-1 (HO-1).Studies showed that CO resembled nitric oxide(NO) in mediating activities related to cyclic guanosine monopho sphate(cGMP) which is another gas signal molecule delineated recently.Previous studies about CO concentrated on its role of distending blood vessel and to be a second neural messenger.Now the role of anti-oxidative injury about CO is the emphasis of studies. Previous reports and the serial studies of our laboratory demonstrated that CO could protect lung when lipopolysaccharide(LPS) is injected through lingual vein. However, there was few report, to our knowledge,whether CO could defenase lung and liver during SS causes by cecal ligation and puncture(CLP).In this study ,using a rat model of CLP-induced SS, we observed the changes of CO level in blood,lung and liver tissues, injury,explored its role and provide new method for clinical doctor to prevent and cure correlative disease duing SS. Method:By using a Sprague-Dawley(SD) rat model of CLP, 96 SD rats were randomly divided into four groups①the Sham group:only traversed a string at cecal root,did not ligate and puncture②CLP group③CLP+Hemin(Hemin, CO donor) group,Hemin(10mg/kg, 10mg/ml,iv)was injected 10min before CLP④CLP+ZnPP(ZnPP, the specific HO-1 inhibitor) group, ZnPP(10mg/kg, 10ml/ml, iv)was injected 10min before CLP. Parameters were observed respectively 2h, 4h, 6h aftersham operation or CLP in each group.Carpbxyhemoglbin(CO-Hb)levels in-flowing pulmonary blood(IPB) and out-going pulmonary blood were detected.The level of COHb represented CO content.The malondialdehyde(MDA) content and the activity of superoxide dismutase(SOD) in the lung,liver and blood were detected using test kits.The pathomorphological changes in the lung and liver were observed under light microscope and immunohistochemical technique was used to detect expression of HO-1 protein in the lung and liver after CLP. Results:①COHb level in OPB was higher than that in IPB in each group(P<0.05).Compared with control group, the level of COHb in OPB and IPB increased in CLP group at 2h,4h,6h after CLP model and the difference of COHb level between OPB and IPB also increased(P<0.05).Compared with CLP group, the parameters mentioned above further increased in CLP+Hemin group (P<0.05).There was no significant difference of these parameters between CLP+ZnPP group and Sham group(P >0.05). ②The MDA content of lung,liver and blood(14.52±1.29nmol/mg protein,13.54±0.45nmol/mg protein, 12.15±0.43 nmol/mg protein)2h after CLP model began to increase compared with Sham group(9.28±0.71nmol/mg protein,8.92±0.58nmol/mg protein, 8.97±0.59nmol/mg protein, P<0.01). After 4h it also increased significantly(16.52±1.32nmol/mg protein, 16.71±0.68nmol/mg protein, 16.25±0.79nmol/mgprotein, P<0.01) and rema...