Changes in L-arginine/nitric oxide pathway of the aorta in septic shock rats

AIM:To observe the change of nitric oxide (NO) generation system in the vascular adventitia, media and intima in septic shock rats.METHODS:The septic shock model was made in rats by caecal ligation and puncture. The intima, media and adventitia of the rat aorta were separated. NO production (NO₂^-), nitric oxide synthase(NOS) activity and L-arginine (L-Arg) transport were measured, separately. Inducible NOS (iNOS) distribution was detected by immunohistochemistry.RESULTS:Both in early and late stage of septic shock, NO₂^- from the intima was decreased by 66.1% and 78.9%(P<0.01), while NO₂^- from the media was increased by 1.1 and 2.2 folds(P＜0.01), and the adventitia 9.6 and 18.6-fold (P＜0.01), as compared with the sham group, respectively. The changes of NOS activity and the L-arginine transport in the intima, the media layer and the adventitia of the aorta in the septic shock rat paralleled with that of NO₂^- in these tissues. The results of iNOS immunohistochemistry showed that there were obviously positive staining in the media layer and adventitia, especially the adventitia of the rat aortas in septic shock, as compared with that in the sham control.CONCLUSIONS:During septic shock, NO production in the aortic intima was progressively suppressed. However, it was progressively increased in the aortic medial layer and adventitia, especially the adventitia with shock processes. These changes result from different changes of L-arginine transport, NOS activity and its expression in three layers of the aorta from the septic shock rat.     

Septic shock down-regulates L -arginine /NOS /NO pathway of platelet and aortic intima in rats

AIM: To investigate alteration and cross link of the aortic and platelet endogenous L -arginine/NOS/NO pathway induced by septic shock.METHODS: The septic shock model was made in rats by caecal ligation and puncture. NO^-₂/NO^-₃ production released from aortic and platelet was measured with Greiss assay. NOS activity and L-arginine transport activity were detected by isotope tracer method. RESULTS: Both in early and late stage of septic shock, NO^-₂/NO^-₃ production, NOS activity, and the L-arginine transport from the aorta intima and platelets were obviously decreased, while those of the aorta media and adventitia were obviously increased (P<0.01), but high-affinity L-arginine transport activity from the aorta intima and platelets was increased in early stage of septic shock (P>0.05 and P<0.05), as compared with the sham group, respectively. The inhibitory effects of NO^-₂/NO^-₃, NOS activity and the L-arginine transport showed a positive correlation between platelet and aortic intima (P<0.01). CONCLUSION: Septic shock down-regulates endogenous L-arginine/NOS/NO pathway in aortic intima and platelet, up-regulates L-arginine/NOS/NO pathway of aortic media and adventitia. Detection of the alteration of endogenous L-arginine/NOS/NO pathway in platelet might act as an indirect method to assess the endothelial dysfunction involving the pathogensis of septic shock.     

Mechanism of mesenteric lymph duct ligation against the renal insufficiency in hemorrhagic shock rats

AIM: To observe the effect of mesenteric lymph duct ligation on free radical and inflammatory mediator in serious hemorrhagic shock rats at different periods, and explore the mechanism of intestinal lymphatic pathway on renal insufficiency. METHODS: 78 male Wistar rats were divided into the sham group, shock group, and ligation group. The model of serious hemorrhagic shock was established in shock group, ligation group, and mesenteric lymph was blocked by ligating mesenteric lymph duct in ligation group after resuscitating. All rats were executed and kidneys were taken out for making homogenate of 10 percent to determine levels of MDA, SOD, NO, NOS, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and myeloperoxidase (MPO) at time points after shock 90 min, after transfusion and resuscitate 0 h, 1 h, 3 h, 6 h, 12 h and 24 h. The expression of inducible nitric oxide synthase (iNOS) mRNA in kindey was detected by RT-PCR. RESULTS: The contents of MDA, NO, NOS, TNF-α, IL-6, MPO and iNOS expressions in renal homogenate of shock group were increased after transfusion and resuscitation, and were higher at 6 h and 12 h, and was significantly higher than that in sham group. The acvitity of SOD was significantly lower than that in sham group (P<0.01, P<0.05). The contents of MDA, NO, NOS, TNF-α, IL-6, MPO and iNOS expression in renal homogenate of ligation group after transfusion and resuscitation 6 h, 12 h and 24 h were significantly lower than those in shock group at same points, and the SOD activity was higher (P<0.01, P<0.05). CONCLUSION: The results demonstrate that the ligation of mesenteric lymph duct can antagonise the development of renal failure in serious hemorrhagic shock rats, and its mechanism might relate to reduce the PMN sequestration, decrease the levels of TNF-α and IL-6, inhibit NO production and expression of iNOS mRNA, suppress the release of free radical and consumption of SOD.     

Effects of PPARβ and NO on high glucose and insulin-induced cardiomyocyte hypertrophy

AIM: To investigate the role of peroxisome proliferator-activated receptor β(PPARβ)-nitric oxide(NO) signal pathway in cardiomyocyte hypertrophy induced by high glucose(25.5 mmol/L) and insulin(0.1 μmol/L)(HGI). METHODS: The cardiomyocyte hypertrophy was characterized in rat primary cardiomyocytes by measuring the cell surface area, protein content, and the mRNA expression of atrial natriuretic factor(ANF). The mRNA and protein expression were measured by real-time PCR and Western blotting, respectively. The activity of NO synthase(NOS) and NO content were measured by a reagent kit through ultraviolet spectroscopy. RESULTS: HGI induced profound change of hypertrophic morphology, and significantly increased the cell surface area, protein content and mRNA expression of ANF(P<0.01), but decreased the expression of PPARβ at mRNA and protein levels(P<0.05). At the same time, the expression of inducible NOS(iNOS) was obviously elevated(P<0.01), which occurred in parallel with the rising NOS activity and NO concentration(P<0.01). GW0742(1 μmol/L), a selective PPARβ agonist, inhibited the cardiomyocyte hypertrophy induced by HGI(P<0.01), and up-regulated the expression of PPARβ at both mRNA and protein levels. Meanwhile, GW0742 also inhibited the increases in iNOS expression, NOS activity, and NO content induced by HGI, which were abolished by GSK0660(1 μmol/L), a selective PPARβ antagonist(P<0.01). CONCLUSION: PPARβ down-regulation and the following iNOS-NO activation are involved in the cardiomyocyte hypertrophy induced by HGI.     

Effect of taurine on L-arginine/NO pathway in erythrocytes of rats of hypertension with insulin resistance induced by fructose

AIM and METHODS:The present study observed the change of L-arginine(L-Arg)/Nitric oxide(NO)pathway in ergthrocytes in hypertension with insulin resistance rat induced by fructose and the effect of taurine on L-Arg/NO pathway.RESULTS:Drinking 4%fructose, while inducing blood pressure, glucose and plasma insulin contents increase, obviously decreased the maximal velocity of L-Arg transport about 31%and 37%(P<0.01), more than that of control group in total and Y⁺ carrier, the NO synthase(NOS)activity, nitrite(NO₂^-)content and cyclic guanylate monophosphate(cGMP)level more than that of control group, but obviously enhanced Michaelis Constant(Km)about 35%and 30%(P<0.01)more than that of control group in total and Y⁺ carrier transport.The taurine treatment significantly counteracted the above changes.CONCLUSION:There exists a functional disturbance in L-Arg/NO system in the erythrocyte of hypertension rats with insulin resistance, but taurine can obviously enhanced the maximal velocity of L-Arg transport and NOS activity.Thus, it appears that taurinemay have vital value in the treatment of hypertension with insulin resistance.     

Effect of chronic hypoxia on L-Arginine/nitric oxide pathway in rat pulmonary artery

AIM: To study the effect of chronic hypoxia on L-Arginine/NO pathway in rat pulmonary artery. METHODS: Changes in pulmonary artery L-Arginine(L-Arg) transport, nitric oxide synthase (NOS) activity, plasma nitrite level and L-Arg level in HPH rats were investigated. RESULTS: (1) The mean pulmonary arterial pressure (mPAP) and weight ratio of right ventricle to left ventricle and septum (RV/LV+S) of HPH group were higher than those in control group (P＜0.01). (2) Plasma L-Arg level in HPH group was not significantly changed. (3) At low (0.2 mmol/L)or high(5.0 mmol/L)concentration of L-Arg, the velocity of L-Arg transport in HPH group was lower than that in control group (P＜0.05 or P＜0.01). (4) The activity of pulmonary artery tNOS, iNOS and cNOS in HPH group were increased by 38.0%, 32.8% and 53.0%, respectively (P＜0.01), compared with control group. (5) Plasma NO level of HPH group was decreased, which was negative correlation to mPAP and RV/LV+S (P＜0.01). CONCLUSION: The decrease of nitric oxide generation might result from L-Arg transport injury, while pulmonary artery tNOS, iNOS and cNOS activity were enhanced during chronic hypoxia.     

Liver protection by Sini decoction in hemorrhagic shock and its mechanism relating to oxygen free radical and nitric oxide

AIM:The work was designed to explore protective effects of a traditional Chinese medicine-sini decoction (SD) on liver in hemorrhagic shock and its mechanism relating to oxygen free radical and nitric oxide.METHODS:Anesthetized Wistar rats were subjected to a hemorrhagic shock protocol for 60 min followed by intravenous injection with normal sodium chloride solution or SD solution. Superoxide dismutase (SOD), malondialdehyde (MDA) and nitric oxide (NO) in liver were examined. The inducible nitric oxide synthase (iNOS) was determined immunohistochemically. RT-polymerase chain reaction (RT-PCR)was used to assay the mRNA, which were corresponding to eNOS (endothelial nitric oxide synthase) and iNOS.RESULTS:The activity of SOD decreased, while the concentration of MDA increased in liver during hemorrhagic shock. SD enhanced SOD activity and inhibited a increase in MDA level in liver (P＜0.01). The NO concentrations in liver in SD group increased at three hours after resuscitation (P<0.01). In addition, it was found that the expression of iNOS was upregulated in sodium chloride-treated group, while SD upregulated the expression of eNOS.CONCLUSION:SD reduces the liver injury caused by oxygen free radicals during hemorrhagic shock. The increasing NO concentration by SD is through upregulation of endothelial NOS expression.     

Mechanism of vascular hyporeactivity induced by NO in hemorrhagic shock

AIM: To investigate the role of nitric oxide (NO) in vascular hyporeactivity during prolonged hemorrhagic shock (HS). METHODS: Anesthetized Sprague-Dawley rats (180-220 g) were subjected to HS insult in which they were bled to a mean arterial pressure (MAP) of 40 mmHg (5.33 kPa) and arteriolar reactivity to norepinephrine in spinotrapezius was detected. The constant MAP of 40 mmHg was maintained until vascular hyporeactivity had occurred and then were resuscitated or sacrificed for further analysis. NO synthase (NOS) activity was measured ex vivo by the conversion of [³H]-arginine to [³H]-citrulline in homogenates from heart, lung, liver, spleen, duodunum, skeletal muscle. 24 h survival rates of resuscitated rats were observed with and without administration of aminoguanidine (AG), a selective inducible NOS (iNOS) inhibitor. Mesenteric arteriolar smooth muscle cells (ASMC) were isolated, and the effects of L-arginine (L-Arg) on membrane potential (MP) of ASMC were determined by fluorescent probe and confocal microscopy in the absence and presence of AG. RESULTS: When vascular hyporeactivity occurred, an increase of NOS activity was observed in liver and heart. Resuscitated rats with AG had a higher survival rate compared with that of control. The MP of ASMC was decreased (more negative) immediately following the addition of L-Arg, and the hyperpolarization effects of L-Arg were partially blocked in the presence of AG. CONCLUSION: These results suggest that excessive NO produced in HS is responsible for the occurrence of vascular hyporeactivity in prolonged hemorrhagic shock, and one of the mechanisms of which may be hyperpolarization of ASMC caused by NO.     

Nitric oxide production,NOS activity and expression in pulmonary arterioles of rats with chronic hypoxic hepercapnic pulmonary hypertension

AIM: To clarify the role of nitric oxide (NO) system in development of chronic hypoxic hypercapnic pulmonary hepertension. METHODS: Male Sprague-Dawley rats were randomly divided into control group and hypoxic hypercapnic group. NO content of plasma was determined, constitutive nitric oxide synthase (cNOS) and inducible nitric oxide synthase (iNOS) were examined using the technique of immunohistochemistry, expression of cNOS mRNA and iNOS mRNA of arteriole were detected by in situ hybridization. RESULTS: Plasma NO concentration, cNOS activity and cNOS mRNA expression in arteriole of chronic hypoxic hypecapnic group were significantly lower than that of control group (P<0.01); activity of iNOS and expression of iNOS mRNA in arteriole showed significantly higher compared with control. CONCLUSION: The disturbance of NO production and NOS expression in arteriole are involved in hypoxic hypercapnic pulmonary hepertension.     

Changes in L-arginine/NO pathway of erythrocytes in patients with essential hypertension

AIM:To investigate the changes of L-arginine/nitric oxide(L-Arg/NO) pathway and the characteristics of L-Arg transport in erythrocytes (RBC) in patients with essential hypertension(EH). METHODS: 12 EH patients were studied with 10 normotensive people as control. The nitric oxide (NO) production was assayed by measuring the nitrite in medium using Greiss reaction. NO synthase activity was measured according to the method described by Ghigo. In order to achieve zero-trans condition, erythrocytes were incubated at 37℃ for 3 h and then L- Arg transport of RBC were determined by measuring the influx of radiolabelled L-arginine by Deliconstantins described method. RESULTS: In EH patients, NO production was lower than that in control (P＜0.01) and the cGMP quantity was only 72.8% of control (P＜0.01). NOS activity of EH patients decreased to 47.8% of control. Saturable influx of L-Arg was mediated by the classical cationic amino acid transport system Y^＋ and Y^＋L system with high affinity. Under zero-trans condition, the ability of L-Arg transport by RBC in EH patient was lower than control. The V_max for total L-Arg transport and via system Y^＋ respectively decreased 36.8% and 42.5% compared with control. But V_max or L-Arg transport via system Y^＋L was not affected by EH. In EH patients K_m value for total, system Y^＋and system Y^＋L had no difference with control. CONCLUSION: The present study suggested that there is disturbance of L-Arg/NO pathway in human erythrocytes from patient with EH.     

Effects of external counterpulsation on nitric oxide system in myocardial infarction canines

AIM:To investigate the effects of external counterpulsation(ECP)on nitric oxide(NO)and nitric oxide synthase(NOS)and the expression of NOS gene in myocardial infarction canines.METHODS:Nineteen healthy dogs were randomly divided into three groups ie.controls, ischemia group, ischemia and ECP group.Serum NO concentrations and myocardium NO levels and NOS specific activity were determined by modified nitrate reductase method.T he protein synthesis of sub-type NOS including inducible NOS(iNOS)and endothelial NOS(eNOS)of myocardial tissue were also determined by immunohistochemical method.The constitutive NOS(cNOS)mRNA was measured via in situ hybridization.RESULTS:120 and 180 minutes after the ligat ing of LAD, serum NO concentration in ECP groups were higher than those in ischemic groups(P<0.05).The NO levels and NOS specific activity in myocardium of ischemic dogs were lower than those in controls and ECP group(P<0.05).Protein synthesis of iNOS increased and that of eNOS decreased in ischemic myocardium.But ECP could control the protein synthesis of iNOS, and increase that of eNOS.Further studies showed that the expression of cNOS mRNA decreased in ischemic myocardial tissue, ECP might promote the expression of it and regulate NOS in the gene level.CONCLUSION:The results suggested that it was one of the most important mechanisms through raising the NO levels to protect ischemic myocardium in ECP.     

Alterations of nitric oxide synthase in cardiac sarcoplasmic reticulum from rats with myocardial calcification

AIM: To study alterations of nitric oxide synthase (NOS) in cardiac sarcoplasmic reticulum from rats with myocardial calcification, and to explore the mechanism of inhibition of SR function in the rats with myocardial calcification. METHODS: Compared with control, myocardial calcium content in the 6 weeks increased by 408%（Ｐ＜0.01）, the NO production, NOS activity and NOS protein expression in the SR with myocardial calcification increased versus control（Ｐ＜0.01）.Myocardial calcium content was not alterations significantly, but the NOS/NO pathway in the SR was up-regulated slightly in the 2 weeks. RESULTS: Compared with control, myocardial calcium content in the 6 weeks increased by 408%(P＜0.01), the NO production, NOS activity and NOS protein expression in the SR with myocardial calcification increased versus control(P＜0.01).Myocardial calcium content was not alterations significantly, but the NOS/NO pathway in the SR was up-regulated slightly in the 2 weeks. CONCLUSION: The up-regulated NOS/NO system in the SR with myocardial calcification is the important mechanism of function inhibition of the SR.     

Effects of cholecystokinin octapeptide on cerebral cortex injury during endotoxic shock

AIM: To study the effects of cholecystokinin octapeptide (CCK-8) on cerebral cortex injury during endotoxic shock (ES) and its mechanisms. METHODS: Rabbits were injected intravenously with lipopolysaccharide (LPS, 8 mg/kg) to establish ES model. Rabbits (n=32, 8 in each group) were randomly assigned to receive one of four treatments intravenously: normal saline (as control), LPS, CCK-8 pretreatment 30 min before LPS, proglumide (Pro, nonspecific antagonist of CCK receptors) pretreatment 30 min before LPS. The changes of mean arterial pressure (MAP) were measured. The morphologic changes in cerebral cortex were observed through light microscope (LM) and transmission electron microscope (TEM). The alterations of activities of nitric oxide synthase (NOS) and superoxide dismutase (SOD), contents of nitric oxide (NO) and malondialdehyde (MDA) in cerebral cortex were assayed. The expressions of protein of inducible NOS (iNOS) and neuronal NOS (nNOS) were detected by immunohistochemistry staining in cerebral cortex in 4 groups of Sprague-Dawley (SD) rats (n=12, 3 in each group) which were grouped as that of the rabbits. RESULTS: LPS administration resulted in lower MAP than that in control group (P<0.01). Hydropic degeneration of neurons and severe injuries to capillaries were observed in cerebral cortex of ES rabbits. LPS administration induced the expression of iNOS protein in the cytoplasm of neurocytes, and lead to stronger positive signals of nNOS than that in control group. NOS activity, NO2ˉ/NO3ˉ level and MDA content were higher (P<0.05, P<0.01 and P<0.01), while SOD activity was lower in cerebral cortex of ES rabbits than those in control group (P<0.01). CCK-8 pre-administration alleviated the changes induced by LPS, while Pro pre-administration aggravated those alterations. CONCLUSION: CCK-8 protects brain tissues against the injury induced by LPS, which may be associated with its effects of suppressing the overproduction of NO and free radicals.     

早熟大粒无核葡萄新品种‘超级无核’

 ‘超级无核’葡萄系从美国引进葡萄新品种‘Superior Seedless’优选单株培育出的优良品种。无核、大粒、早熟、优质、早实、丰产、生长势强健、耐病、耐不利栽培条件, 是适合高温、高湿、少日照地区栽培的无核葡萄新品种。     

Effect of nitric oxide on urotensin-Ⅱ expression in pulmonary arterioles of rats chronically exposed to hypoxia-hypercapnia

AIM: To investigate the roles of nitric oxide/L-arginine (NO/L-Arg) pathway and urotensin-Ⅱ (UⅡ) in the development of pulmonary hypertension induced by chronic hypoxia-hypercapnia in rats.METHODS: Forty male Sprague-Dawley rats were randomly divided into four groups (n=10): normal control group (A), hypoxia-hypercapnia+saline group (B), hypoxia-hypercapnia+L-Arg liposome group (C) and hypoxia-hypercapnia+N-nitro-L-arginine methyl ester (L-NAME) group (D).Contents of UⅡ, UⅡ mRNA and receptor of UⅡ (UT) mRNA in pulmonary arterioles were measured with immunohistochemistry analysis and in situ hybridization, respectively.Change of small pulmonary vascular microstructure was also investigated.RESULTS: (1) The mean pulmonary artery pressure (mPAP) and the weight ratio of right ventricle to left ventricle plus septum ［RV/(LV+S)］ in B and D groups were all higher than those in A group (respectively, P<0.05), with C group significantly lower than those in B group (respectively, P<0.01).(2) Light microscopy showed that the ratio of vessel wall area to total area (WA/TA) and the media thickness of pulmonary arterioles (PAMT) in B group were higher than those in A group (P<0.05), with C group significantly lower than those in B group.(3) The contents of UⅡ, UⅡ mRNA and UT mRNA in pulmonary arterioles in B and D groups were all higher than those in A group (respectively, P<0.01), while the expression of UⅡ and UⅡ mRNA in C group were lower than those in B group (P<0.01).CONCLUSION: The pathological process of pulmonary hypertension induced by chronic hypoxia-hypercapnia might be related to upregulation of UⅡ located in pulmonary arterioles, which might be partially inhibited by exogenous NO in rats.     

Effect of mesenteric lymph duct ligation on actue lung injury in rats

AIM：To explore the effect of mesenteric lymph duct ligation against actue lung injury (ALI) in rats.METHODS：45 Wistar rats were divided into three groups：the ligation group,the non-ligation group and sham operated group,and the two-hit model was established by hemorrhage and LPS injection.Mesenteric lymph was diverted by ligating mesenteric lymph duct in ligation group.All rats facilitated blood withdrawal for blood sample to arterial gas analysis after 24 hours.Then the WBC,NO,NOS,MDA,SOD and lung permeability index (LPI) were determined in bronchoalveolar lavage fluid (BALF),the MPO and ATPase activity were determined in lung homogenate.The ultrastructure was also observed.RESULTS：After two-hit,the PaCO2,the total cells and PMN,the NO2-/NO3-,NOS and MDA content in BALF and MPO activity in lung homogenate and LPI in non-ligation group were significantly increased than those in sham operated group.PaO2 and pH in arterial blood,SOD in BALF and the ATPase in lung homogenate were significantly lower (P<0.01 or P<0.05).The total cells and PMN,MDA,NO2-/NO3- in BALF,LPI in ligation group were significantly increased than those in sham operated group,and SOD in BALF was significantly lower (P<0.01 or P<0.05).The pH and PaO2 in arterial blood,the ATPase in lung homogenate in ligation group were significantly increased than those in non-ligation group,and the PaCO2,the total cells,PMN,NO2-/NO3-,NOS,MDA in BALF,LPI,and MPO in lung homogenate in ligation group were significantly lower than those in non-ligation group (P<0.01 or P<0.05).The injury of pulmonary vascular endothelium in ligation group was lighter than that in non-ligation group.CONCLUSION：The ligation of mesenteric lymph duct attenuates the ALI of rats.Mesenteric lymph might play an important role in the pathogenesis of ALI.     

Role of polyamines in L-arginine inhibiting isoproterenol induced cardiac hypertrophy rat

AIM: To explore the role and possible mechanism of polyamine in L-arginine inhibiting cardiac hypertrophy induced by isoproterenol (ISO). METHODS: Hypertrophic model of rats was established using ISO. Pretreated with L-arginine, hypertrophy status of rats was determined by hypertrophy coefficient, collagen content and the expression of ANP mRNA. High performance liquid chromatography (HPLC) was used to measure the concentrations of polyamines. Western blotting was performed to detect the expressions of ornithine decarboxylase (ODC) and spermidine/spermine N1-acetyltransferase (SSAT). The activity and levels of NOS and NO in serum were also observed. RESULTS: Hypertrophy coefficient and expression of ANP mRNA increased significantly after injection of ISO for 7 d. Moreover, cardiac muscle fibres became thick and disorganized. Pretreated with L-arginine, the above index decreased. Meanwhile, the concentration of polyamine was decreased and plasma NO content and NOS activity were increased, the expression of ODC was downregulated and the expression of SSAT was upregulated. CONCLUSION: Exogenous L-arginine inhibits cardiac hypertrophy through downregulating L-arginine/polyamine pathway and upregulating L-arginine/NO pathway.     

Changes of nitric oxide synthase and nitric oxide in lung of smoking rats

AIM:To observe the changes of iNOS and eNOS in lung tissue and NO in bronchoalveolar lavage fluid (BALF) in smoking rats.METHODS:80 Wistar rats were divided into control, smoking group, L-NIL group and L-NAME group (rats were exposed to smoke and injected (i.p.) with selective iNOS inhibitor L-NIL or NOS inhibitor L-NAME). iNOS and eNOS protein levels in whole lung were detected by immunohistochemical staining, and NOS mRNA was quantified using RT-PCR. In addition, NO₂^-/NO₃^- was determined using Griess assay.RESULTS:The expression of iNOS mRNA and protein in smoking rats increased, the expression of eNOS mRNA and eNOS protein decreased, and the total cell count and the level of NO₂^-/NO₃^-in BALF increased(P＜0.05). In vivo, L-NIL reduced the total cell count and NO₂^-/NO₃^- in BALF (P＜0.05), while L-NAME had no effect on them.CONCLUSION:Cigarette smoke increased expression of iNOS mRNA and protein and decreased expression of eNOS mRNA and protein. The large amount of NO generated by iNOS may amplify inflammation in lung tissue.