Real-time monitoring of nitric oxide in ischemia-reperfusion rat kidney

In this study we attempted to clarify the release of nitric oxide (NO) and its role in the ischemia-reperfusion rat kidney. After right nephrectomy, male Wistar rats were divided into four groups: one sham operated and three groups who underwent ischemia (30 min) and reperfusion of the left renal artery. Thirty minutes prior to ischemia-reperfusion, two groups were injected intraperitoneally with 10 and 30 mg/kg of NG-nitro-L-arginine methylester (L-NAME). Real-time monitoring of blood flow and NO release in the rat kidney was measured with a laser Doppler flowmeter and an NO-selective electrode, respectively. Serum creatinine and blood urea nitrogen (BUN) levels were measured 1 and 7 days after the induction of ischemia-reperfusion. Clamping of the renal artery decreased blood flow to 1-5% of the basal level measured before clamping. After removal of the clip, the blood flow of the 30 mg/kg L-NAME rats was significantly lower than that of the controls. Immediately following the clipping of the renal artery, NO release rapidly increased. After removing the clip, NO release immediately returned to three-quarters of the basal level. Serum creatinine and BUN levels of the ischemia-reperfusion rats were slightly but not significantly higher and those of 30 mg L-NAME rats were significantly higher than those of the control or ischemia-reperfusion rats 1 day and 7 days after ischemia-reperfusion. Our data suggest that NO acts as a cytoprotective agent in ischemia-reperfusion injury of the rat kidney.     

Multiparametric monitoring of ischemia-reperfusion in rat kidney: effect of ischemic preconditioning

BACKGROUND: Microelectrode technology is a promising tool for monitoring kidney ischemia and the changes induced by its therapeutic management. Ischemic preconditioning, that is, brief ischemic periods before sustained ischemia, has been shown to protect several organs, including the kidney, from ischemia-reperfusion injury. We tested whether the effect of preconditioning could be appraised by real-time measurement of parameters representative of tissue hypoxia. METHODS: In a sample of pentobarbital-anesthetized and mechanically ventilated rats, we studied the effect of renal ischemic preconditioning (10-min ischemia and 10-min reflow interval) on subsequent ischemia-reperfusion (45 min and 60 min). Renal tissue electrical impedance, extracellular pH, and potassium concentration [K+] were measured continuously by implanted microelectrodes. RESULTS: Ischemia induced an early, rapid rise in extracellular potassium and impedance module, followed by a phase of slower increase, whereas pH decreased rapidly, reaching a plateau. Preconditioning treatment did not cause significant changes in interstitial pH and [K+] but increased ischemic tissue impedance. During reperfusion, the three variables recovered progressively; however, after a decline, electrical impedance showed a clear postischemic increase. This rise was suppressed by preconditioning. CONCLUSIONS: Real-time measurement of any of the three parameters showed capability for early detection of ischemia. In contrast with findings in myocardial tissue, preconditioning in the kidney did not increase potassium cell loss during ischemia or improve ischemic acidosis or tissue impedance. Electrical impedance increased for a second time during reperfusion, indicating the presence of a postischemic cellular edema; concealing this episode was the most noticeable effect of the preconditioning treatment.     

缺血预处理对大鼠肝脏缺血再灌注损伤的保护机制

目的验证缺血预处理(IPC)对大鼠肝脏缺血再灌注损伤(I/R)的保护作用,探讨一氧化氮(NO)与蛋白激酶C(PKC)在IPC过程中的作用.方法在原位灌流的大鼠肝脏缺血再灌注模型上,观察IPC的保护作用.同时经肠系膜上静脉注射NO前体L-精氨酸和蛋白激酶C特异性激动剂1,2-二辛酸甘油(DOG)以及两者的特异性阻滞剂N-硝基-L-精氨酸甲酯(NAME)和多粘菌素B,来检测NO和PKC在IPC中的关系.结果预处理可阻止血清谷丙转氨酶(ALT)[(200.86±40.30)U/Lvs.(257.65±20.18)U/L],谷草转氨酶(AST)[(211.06±13.59)U/Lvs.(309.17±24.79)U/L],乳酸脱氢酶(LDH)[(824.73±127.11)U/Lvs.(1118.60±82.21)U/L]及脂质过氧化物(LPO)[(0.414±0.069)mmol/mgvs.(0.531±0.054)mmol/mg]水平升高(P＜0.05),而使组织超氧化歧化酶(SOD)保持在较高水平[(10.33±0.88)U/mgvs.(6.01±0.91)U/mg],(P＜0.05).NO与PKC均可模拟预处理的保护效应.结论缺血预处理对大鼠肝脏I/R有明确的保护作用,NO与PKC发挥IPC保护作用的途径不同.     

一氧化氮在大鼠小肠移植缺血再灌注损伤和急性排斥反应中的作用

目的 探讨一氧化氮(NO)在大鼠小肠移植缺血再灌注损伤(IRI)和急性排斥反应(AR)中作用.方法 建立同种大鼠原位小肠移植模型,采用随机数字表法将受鼠分为4组.移植对照组、左旋精氨酸(L-Arg)组、左旋硝基精氨酸甲酯(L-NAME)Ⅰ组(Ⅰ组)和L-NAMEⅡ组(Ⅱ组)受鼠于手术当天开始分别每天给予生理盐水、L-Arg 150 mg·kg-1 ·d-1、L-NAME 4和8 mg·kg-1·d-1.术后观察各组受鼠的存活时间,行HE染色观察移植小肠的组织病理学改变,采用免疫组织化学法观察移植小肠一氧化氮合酶(NOS)的活性,以及检测血糖吸收功能和血清NO浓度.结果 移植对照组、L-Arg组、Ⅰ组及Ⅱ组受鼠的存活时间分别为(11.7±1.2)d、(10.2±1.0)d、(12.3±1.5)d和(17.3±1.9)d,Ⅱ组受鼠的存活时间明显延长(P＜0.01).与移植对照组相比,L-Arg组和Ⅰ组IRI的Park评分下降,IRI减轻;Ⅱ组Park评分显著升高(P＜0.01),IRI加重,但AR明显减轻.与移植对照组相比,IRI期间,Ⅰ组iNOS染色减弱,Ⅱ组iNOS和nNOS染色均减弱;AR期间,Ⅱ组iNOS染色明显减弱.各组血清NO浓度于再灌注后30min逐渐升高.与移植对照组相比,Ⅱ组血 NO浓度的升高延缓.与移植对照组相比,L-Arg组血糖吸收值于再灌注30 min至术后3d明显增高(P＜0.01);Ⅰ组和Ⅱ组血糖吸收值术后处于较低水平.结论 NO在大鼠小肠移植IRI中起到了细胞毒和细胞保护的双重作用;在AR中加重了组织损伤.术后早期补充L-Arg可促进移植肠管对糖类的吸收.     

Ischemic preconditioning in solid organ transplantation: from experimental to clinics

This study reviews the current understanding of ischemic preconditioning (IP) in experimental and clinical setting, and the mechanisms that mediate the complex processes involved as a tool to protect against ischemia and reperfusion (I/R) injury, but is not intended as a complete literature review of preconditioning. IP has been mainly elucidated in cardiac ischemia. Recent reports confirm the efficacy of pre- and postconditioning in cardiac surgery and percutaneous coronary interventions in humans. IP utilizes endogenous as well as distant mechanisms in skeletal muscle, liver, lung, kidney, intestine and brain in animal models to convey varying degrees of protection from I/R injury. Specifically, preconditioned tissues exhibit altered energy metabolism, better electrolyte homeostasis and genetic reorganization, as well as less oxygen-free radicals and activated neutrophils release, reduced apoptosis and better microcirculatory perfusion. To date, there are few human studies, but recent trials suggest that human liver, lung and skeletal muscle acquire protection after IP. Present data address the potential therapeutic application of IP in the prevention of I/R damage specially aimed at clinical transplantation. IP is ubiquitous but more research is required to fully translate these findings to the clinical arena.     

应用电子顺磁共振技术研究大鼠肾移植缺血再灌注过程中的NO水平及变化

目的应用电子顺磁共振(EPR)技术动态监测大鼠移植肾缺血再灌注过程中一氧化氮(NO)的产生及其作用. 方法雄性LEW大鼠75只,8～10周龄,体重200～230 g.30只作为供体,供肾0 ℃保存24 h.其余45只分3组,每组15只.第1组为对照组,麻醉后开腹,暴露30 min后关腹;第2组为单纯肾移植组,行同基因肾移植,移植肾再灌注同时切除双肾;第3组为肾移植加N-硝基-L-精氨酸甲脂(L-NAME)组,移植肾再灌注同时切除双肾,供体和受体术前2 h分别给予L-NAME 30 mg/kg.应用EPR动态测定移植肾恢复血流前及之后各时间点NO水平.测定恢复血流后24 h和120 h血肌酐、肾小球滤过率及肾组织羰基含量. 结果单纯肾移植组再灌注后15 min NO开始显著增加并持续上升,120 min达较高水平后迅速下降,到210 min恢复再灌注前水平;肾移植加L-NAME组呈类似变化趋势,但NO水平明显低于前组.L-NAME组的24 h和120 h血肌酐水平均显著高于单纯移植组(P<0.05);24 h(P<0.05)和120 h(P<0.01)肾小球滤过率均显著低于移植组.L-NAME组的24h组织羰基含量显著低于单纯移植组(P<0.05),120 h高于单纯移植组(P<0.05). 结论冷缺血移植肾再灌注过程中,NO早期增加并迅速下降,对移植肾以保护为主.应用L-NAME抑制NO后不利于移植肾功能恢复.     

Endogenous nitric oxide and exogenous nitric oxide supplementation in hepatic ischemia-reperfusion injury in the rat

BACKGROUND: Although nitric oxide (NO) is thought to be beneficial in hepatic ischemia-reperfusion (I/R), the mechanisms for this effect are not well established. METHODS: To investigate the effects of endogenous NO and exogenous NO supplementation on hepatic I/R injury and their pathogenic mechanisms, serum ALT and hyaluronic acid (endothelial cell damage), and hepatic malondialdehyde and H2O2 (oxidative stress), myeloperoxidase activity (leukocyte accumulation), and endothelin (vasoconstrictor peptide opposite to NO) were determined at different reperfusion periods in untreated rats and rats receiving L-NAME, L-NAME+L-arginine, and spermine NONOate (exogenous NO donor). RESULTS: After reperfusion every parameter increased in untreated animals. Endogenous NO synthesis inhibition by L-NAME increased hepatocyte and endothelial damage as compared to untreated rats, which was reverted and even improved by the addition of L-arginine. Spermine NONOate also improved this damage. However, different mechanisms account for the beneficial effect of endogenous and exogenous NO. Oxidative stress decreased by both L-NAME and L-NAME+L-arginine, but remained unmodified by spermine NONOate. Myeloperoxidase increased by L-NAME and this effect was reverted by the addition of L-arginine, whereas no change was observed with spermine NONOate. Endothelin levels were not modified by L-NAME and L-NAME+L-arginine, but decreased with spermine NONOate. CONCLUSIONS: These results suggest that, although both endogenous and exogenous NO exert a protective role in experimental hepatic I/R injury, the mechanisms of the beneficial effect of the two sources of NO are different.     

Roles of nitric oxide, malondialdehyde, and fibronectin in an experimental peripheral nerve ischemia-reperfusion model

Although there are many studies of the neuropathology of the ischemic degeneration of peripheral nerves, the pathogenesis is not well-understood. The roles of several biomolecules on this process were previously reported. An adhesion molecule, fibronectin, which is applied locally (as a conduit material), is very effective in nerve recovery. This study was carried out to evaluate the roles of fibronectin, lipid peroxidation, and nitric oxide (NO) in an experimental model of peripheral nerves. Ischemia and reperfusion injury of sciatic nerves was rendered by clamping the femoral artery and vein. Rats were divided into nine groups. Ischemia and reperfusion were not applied to group 1. In group 2, only ischemia was performed, but reperfusion was not accomplished. For groups 3-9, 1, 2, and 24 h and 1, 2, 3, and 4 weeks of reperfusion were applied following 3 h of ischemia. Then NO, malondialdehyde (MDA), and fibronectin levels were observed in serum samples of rats. Colorimetric and nephelometric assays were used for determination of the levels of these parameters. In this study, all biochemical parameters were found to be increased in the ischemia groups when compared with the control group 1 (P < 0.05). A significant difference was observed between study groups with respect to MDA, NO, and fibronectin levels (P < 0.05). Also, some correlations were established between biochemical parameters in the same group, depending on the varying reperfusion time (r > 0.50). Ischemia causes some important changes in biochemical parameters, and depending on the reperfusion time, nerve injury continues for a while. In our study, we observed that serum levels of MDA decreased in the periods when NO and fibronectin simultaneously increased. Such increases may contribute to neural recovery, and there may be interactions among them.     

缺血预处理对糖尿病大鼠在体心肌NO-cGMP表达的影响

目的 通过糖尿病大鼠心肌在缺血预处理(IPC)后环磷酸鸟苷(cGMP)及一氧化氮(NO)、一氧化氮合酶(NOS)表达的变化,探讨糖尿病抑制IPC心肌保护作用的机制.方法 取糖尿病及非糖尿病SD大鼠各30只,各分为3组(每组10只).(1)假手术组(Sham组):开胸后穿线做套环,但不收紧结扎线;持续155 min,全程旷置作为基础对照.(2)缺血再灌注组(I/R组):穿线平衡35 min后,持续收紧结扎造成缺血30 min,放松后再灌注90 min.(3)IPC组:穿线平衡35 min后,缺血5min,再灌注5 min,反复3次,而后重复I/R组操作.比较各组血清肌酸激酶(CK)、肌酸激酶同工酶(CK-MB)及乳酸脱氢酶(LDH)的变化,心肌组织丙二醛(MDA)含量和超氧化物岐化酶(SOD)活性及心肌组织cGMP、NO、NOS含量的变化.电镜标本行线粒体Flameng评分.结果 非糖尿病IPC组与I/R组比较,心肌酶漏出明显减少,MDA含量明显降低,SOD含量明显增加,线粒体损伤明显减轻,cGMP、NO、NOS含量明显增加(P＜0.05);而IPC在糖尿病大鼠未表现出明显心肌保护作用,cGMP、NO、NOS含量无明显增加(P＞0.05).结论 糖尿病抑制IPC的心肌保护作用,其机制可能与糖尿病大鼠心肌NO-cGMP通路表达受抑制有关.     

Sirolimus attenuates chronic allograft nephropathy in an experimental rat kidney transplantation model

Chronic allograft nephropathy (CAN) is the primary reason for late allograft loss in kidney transplantation. The use of calcineurin inhibitors is suggested to be a risk factor for the development of CAN. Thus, calcineurin-inhibitor-free immunosuppressive protocols are needed to improve long-term graft outcome. Sirolimus affects the immune response by interfering with postreceptor interleukin-2 signaling. Safety profile of sirolimus is different from that of calcineurin inhibitors. We investigated the long-term effects of sirolimus on kidney allografts and fibrogenic growth factor expression and compared it to cyclosporine A. Kidney transplantations were performed from DA to WF rats and syngenic controls were done between DA rats. Allograft recipients were immunosuppressed daily with sirolimus 2 p.o. or CsA 1.5 mg/kg s.c. In addition, sirolimus-treated animals were treated with cyclosporine 1.5 mg/kg s.c. for the first 7 days after transplantation. Serum creatinine levels were measured once a week. Grafts were harvested 90 days after transplantation for histology and immunohistochemistry. Histological changes were scored according to the chronic allograft damage index (CADI). No signs of CAN were seen in syngenic grafts, CADI 0.8 +/- 0.2 (mean +/- SEM). In cyclosporine-treated allografts moderate to intense chronic changes were seen; CADI 10.3 +/- 0.6. Sirolimus significantly ameliorated the development of CAN compared to cyclosporine, CADI 3.0 +/- 0.5 (P < .05). Creatinine values of sirolimus-treated allografts were lower compared to the cyclosporine-treated allografts and were nearly similar to the syngenic grafts. Our results demonstrate that sirolimus attenuates the development of CAN and restores kidney function. Based on our findings, sirolimus improves the long-term kidney graft outcome.     

Ischemic preconditioning improves energy state and transplantation survival in obese Zucker rat livers

Livers from obese donors often have fatty infiltrates and are more susceptible to ischemia-reperfusion injury and subsequent graft dysfunction. This often leads to the exclusion of organs from obese donors. We investigated whether ischemic preconditioning (IP, 10 min ischemia, 10 min reperfusion) preserves cellular metabolism in livers from obese Zucker rats during cold ischemia. Liver samples (-IP and +IP) were collected from obese and control lean rats at different time points of cold ischemia (CI) and analyzed by magnetic resonance spectroscopy (1H- and 31P-MRS) to assess whether IP improves hepatic cellular metabolism. IP significantly improved high energy metabolism in IP livers from obese rats when compared with obese controls during the first hours of CI. At 4 h of cold storage, obese IP livers were not different from control lean non-IP livers. The beneficial metabolic effect of IP on livers form obese rats, however, was absent at 8 h of reperfusion. In contrast, in livers from lean rats, IP resulted in improved high-energy metabolism during the entire observation period of 8 h. In a later part of the study, IP of liver grafts from obese rats before 4 h of cold storage improved recipient survival after graft transplantation. IP of liver grafts from obese rats before 4 h of CI increases 24-h survival of recipient animals from 25% to 88%.     

Role of nitric oxide in the mechanism of preclamping and remote ischemic preconditioning of adipocutaneous flaps in a rat model

The purpose of this study was to determine whether nitric oxide (NO) plays a role in the mechanism of acute ischemic preconditioning (IP). Fifty-eight male Wistar rats were divided into seven experimental groups. An extended epigastric flap was raised in one of the control groups (C, n = 8), and a 3-hr flap ischemia was induced. Another group served as a non-ischemic control (CO, n = 8). The animals of group S (n = 9) received 500 nmol/kg of Spermine/Nitric Oxide Complex (Sper/NO) intravenously 30 min prior to ischemia. The group N+P (L-NAME + preclamping, n = 8) received 10 mg/kg Nomega-Nitro-L-Arginine Methyl Ester (L-NAME) intravenously before preclamping of the flap pedicle (10-min cycle length, 30-min reperfusion). Ten mg/kg L-NAME were administered in group N+T (L-NAME + tourniquet, n = 9) before ischemia of the right hindlimb was induced using a tourniquet for 10 min after flap elevation. Flap ischemia was induced after 30 min of limb reperfusion. A similar protocol was used in the groups N+P+S (L-NAME + preclamping+Sper/NO, n = 8) and N+T+S (L-NAME + tourniquet + Sper/NO, n = 8). In both groups Sper/NO was administered 30 min prior to flap ischemia, additionally to the protocol of the groups N+P and N+T. Mean flap necrosis area was assessed on the fifth postoperative day using a planimetry software. Average flap necrosis area was 67 +/- 16 percent in the control group C, 28 +/- 13.3 percent in the non-ischemic controls (CO), 10 +/- 5.9 percent in group S, 77.5 +/- 10.2 percent in group N+P, 76 +/- 6.9 percent in group N+T, 71.5 +/- 9.4 percent in group N+P+S, and 78 +/- 9.9 percent in group N+T+S. The animals of group S and CO demonstrated a significantly lower area of flap necrosis than all other groups ( p < 0.001). No significant difference could be shown between the groups C, N+P, N+T, N+P+S and N+T+S. Group S showed a significantly lower flap necrosis area than group CO ( p < 0.01). The data showed, that NO plays an important role in the mechanism of IP since the administration of an NO-donor previous to ischemia simulates the effect of IP, while the unspecific blocking of NO synthesis by L-NAME eliminates the protective effect of flap preconditioning by preclamping as well as by remote IP. Exogenous NO application is insufficient to provide protection once the endogenous NO synthesis is blocked.     

Diazoxide decreases ischemia-reperfusion injury in a rat model of lung transplantation

Background

Ischemia-reperfusion injury (IRI) is a significant factor contributing to primary graft failure in lung transplantation. Given a pivotal role of mitochondria in IRI-related molecular events, the effects of diazoxide, a selective opener of mitochondrial adenosine-5′-triphosphate (ATP)-sensitive potassium channels (mitoK_ATP), on IRI were investigated in a rat model of lung transplantation.

Methods

The 108 rats were randomly assigned to 5 groups; a sham-operated, 2 control, and 2 experimental groups that received either diazoxide alone or a combination of diazoxide with 5-hydroxydecanoate sodium salt. Lung injuries were assessed by multiple parameters at 2 hours or 24 hours after reperfusion, including oxygenation index, wet/dry weight ratio of transplanted lungs, lung morphology, as well as measurements of myeloperoxidase, malondialdehyde, total antioxidant capacity, tumor necrosis factor-α, and interleukin-6.

Results

Compared with the sham group, the 2 control groups revealed significant changes among most parameters of lung injury measured at either 2 hours or 24 hours after reperfusion. The extent of the changes was dramatically reduced by the administration of diazoxide. Importantly, the protective effect of diazoxide was almost completely reversed by co-administration of 5-hydroxydecanoate sodium salt, a selective blocker of mitoK_ATP.

Conclusions

These data provide evidence for substantial protective effects of diazoxide in an in vivo rat lung IRI model. Pharmacological modulation of mitoK_ATP may be a potential strategy to reduce IRI-induced primary graft failure in lung transplantation.     

Ischemic preconditioning: lack of delayed protection against skeletal muscle ischemia-reperfusion

We investigated the ability of ischemic preconditioning to induce expression of heat shock protein 70 (Hsp 70) and/or to increase muscle survival after ischemia-reperfusion in the rat hind limb. Ischemic preconditioning regimens tested were; 1 x 5 min of ischemia, 4 x 5 min of ischemia interrupted by 10 min of reperfusion, 1 x 10 min of ischemia or 2 x 10 min of ischemia interrupted by 15 min of reperfusion. Western blot analysis revealed only a modest induction of Hsp 70 at 24 h after preconditioning using the latter two protocols of 1 x 10 min of ischemia or 2 x 10 min. Used at 24 h prior to prolonged ischemia, neither protocol improved muscle survival measured at 24 h after reperfusion. In conclusion, ischemic preconditioning did not produce delayed protection from ischemia-reperfusion in this model and the study suggests that ischemic preconditioning is not a useful protective strategy against skeletal muscle necrosis in the long-term.     

辛伐他汀预处理对脓毒症大鼠胸主动脉诱导型一氧化氮合酶及内皮型一氧化氮合酶表达的影响

目的 探讨辛伐他汀预处理对脓毒症大鼠胸主动脉诱导型一氧化氮合酶(iNOS)及内皮型一氧化氮合酶( eNOS)表达的影响.方法 清洁级雌性Wistar大鼠80只,4月龄,体重200～250 g,采用随机数字表法,将其随机分为4组:正常对照组(Ⅰ组,n=8)、假手术组(Ⅱ组,n=8)、脓毒症组(Ⅲ组,n=32)和辛伐他汀预处理组(Ⅳ组,n=32).Ⅱ组打开腹腔找到盲肠后还纳腹腔,缝合腹壁切口.Ⅲ组和Ⅳ组采用盲肠结扎穿孔法制备大鼠脓毒症模型.Ⅳ组制备脓毒症模型前经胃管灌注辛伐他汀20 mg/kg,1次/d,连续2周,Ⅰ组～Ⅲ组给予等容量生理盐水.Ⅱ组于假手术后6h处死动物,Ⅲ组和Ⅳ组于盲肠结扎穿孔后3、6、24、48 h分别取8只动物,处死,取胸主动脉,采用Western blot法测定iNOS和eNOS表达水平.结果 与Ⅰ组比较,Ⅱ组iNOS和eNOS表达差异无统计学意义(P＞0.05),Ⅲ组和Ⅳ组iNOS表达上调,eNOS表达下调(P＜0.05);与Ⅲ组比较,Ⅳ组iNOS表达下调,eNOS表达上调(P＜0.05).结论 辛伐他汀预处理可下调脓毒症大鼠血管内皮细胞iNOS表达和上调血管内皮细胞eNOS表达,对血管内皮细胞功能有保护作用.     

Inhaled nitric oxide affects endogenous surfactant in experimental lung transplantation

BACKGROUND: Inhalation of nitric oxide (NO) has been proposed as a therapy to improve lung transplantation outcome. We investigated the effect that inhaled NO has on the surfactant system in the context of ischemia-reperfusion injury. METHODS: Single left-lung transplantation was performed in weight-matched pairs of Landrace pigs. A double-lung block from the donor animal was flushed with University of Wisconsin solution at 4 degrees C followed by immersion in cold University of Wisconsin solution for 22 hr. The left donor lung was transplanted into the recipient. Recipients were divided into two groups: (1) treated with inhaled NO (40 ppm) (n=6) immediately after initiating lung reperfusion and (2) without treatment (n=6). Lung function was measured during 2 hr of reperfusion. Surfactant components in small and large aggregates, isolated from cell-free bronchoalveolar lavages, and surfactant function were measured. RESULTS: NO inhalation significantly decreased arterial oxygenation. With respect to the surfactant system, NO inhalation worsened the surfactant adsorption rate to an air-liquid interface and affected levels of hydrophobic surfactant proteins (SPs), SP-B and SP-C, and phospholipids, which decreased in large surfactant aggregates but not in small surfactant aggregates. SP-A was reduced in large surfactant aggregates of transplanted lungs from both untreated and NO-treated groups. CONCLUSION: A decreased level of SP-A, SP-B, and SP-C in large surfactant aggregates of transplanted lungs treated with NO is a marker of lung injury. We conclude that treatment with inhaled NO after lung transplantation is deleterious for the surfactant system and causes a parallel worsening of arterial oxygenation.