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PubMed1998

Modeling bronchial circulation with application to soluble gas exchange: description and sensitivity analysis.

The steady-state exchange of inert gases across an in situ canine trachea has recently been shown to be limited equally by diffusion and perfusion over a wide range (0.01-350) of blood solubilities (betablood; ml . ml-1 . atm-1). Hence, we hypothesize that the exchange of ethanol (betablood = 1,756 at 37 degrees C) in the airways depends on the blood flow rate from the bronchial circulation. To test this hypothesis, the dynamics of the bronchial circulation were incorporated into an existing model that describes the simultaneous exchange of heat, water, and a soluble gas in the airways. A detailed sensitivity analysis of key model parameters was performed by using the method of Latin hypercube sampling. The model accurately predicted a previously reported experimental exhalation profile of ethanol (R2 = 0.991) as well as the end-exhalation airstream temperature (34.6 degrees C). The model predicts that 27, 29, and 44% of exhaled ethanol in a single exhalation are derived from the tissues of the mucosa and submucosa, the bronchial circulation, and the tissue exterior to the submucosa (which would include the pulmonary circulation), respectively. Although the concentration of ethanol in the bronchial capillary decreased during inspiration, the three key model outputs (end-exhaled ethanol concentration, the slope of phase III, and end-exhaled temperature) were all statistically insensitive (P > 0.05) to the parameters describing the bronchial circulation. In contrast, the model outputs were all sensitive (P < 0.05) to the thickness of tissue separating the core body conditions from the bronchial smooth muscle. We conclude that both the bronchial circulation and the pulmonary circulation impact soluble gas exchange when the entire conducting airway tree is considered.

Administration, Inhalation↗
PubMed1999

Simultaneous measurement of nitric oxide production by conducting and alveolar airways of humans.

Human airways produce nitric oxide (NO), and exhaled NO increases as expiratory flow rates fall. We show that mixing during exhalation between the NO produced by the lower, alveolar airways (VL(NO)) and the upper conducting airways (VU(NO)) explains this phenomenon and permits measurement of VL(NO), VU(NO), and the NO diffusing capacity of the conducting airways (DU(NO)). After breath holding for 10-15 s the partial pressure of alveolar NO (PA) becomes constant, and during a subsequent exhalation at a constant expiratory flow rate the alveoli will deliver a stable amount of NO to the conducting airways. The conducting airways secrete NO into the lumen (VU(NO)), which mixes with PA during exhalation, resulting in the observed expiratory concentration of NO (PE). At fast exhalations, PA makes a large contribution to PE, and, at slow exhalations, NO from the conducting airways predominates. Simple equations describing this mixing, combined with measurements of PE at several different expiratory flow rates, permit calculation of PA, VU(NO), and DU(NO). VL(NO) is the product of PA and the alveolar airway diffusion capacity for NO. In seven normal subjects, PA = 1.6 +/- 0.7 x 10(-6) (SD) Torr, VL(NO) = 0.19 +/- 0.07 microl/min, VU(NO) = 0.08 +/- 0.05 microl/min, and DU(NO) = 0.4 +/- 0.4 ml. min(-1). Torr(-1). These quantitative measurements of VL(NO) and VU(NO) are suitable for exploring alterations in NO production at these sites by diseases and physiological stresses.

Humans↗
PubMed2004

Probing the impact of axial diffusion on nitric oxide exchange dynamics with heliox.

Exhaled nitric oxide (NO) is a potential noninvasive index of lung inflammation and is thought to arise from the alveolar and airway regions of the lungs. A two-compartment model has been used to describe NO exchange; however, the model neglects axial diffusion of NO in the gas phase, and recent theoretical studies suggest that this may introduce significant error. We used heliox (80% helium, 20% oxygen) as the insufflating gas to probe the impact of axial diffusion (molecular diffusivity of NO is increased 2.3-fold relative to air) in healthy adults (21-38 yr old, n = 9). Heliox decreased the plateau concentration of exhaled NO by 45% (exhalation flow rate of 50 ml/s). In addition, the total mass of NO exhaled in phase I and II after a 20-s breath hold was reduced by 36%. A single-path trumpet model that considers axial diffusion predicts a 50% increase in the maximum airway flux of NO and a near-zero alveolar concentration (Ca(NO)) and source. Furthermore, when NO elimination is plotted vs. constant exhalation flow rate (range 50-500 ml/s), the slope has been previously interpreted as a nonzero Ca(NO) (range 1-5 ppb); however, the trumpet model predicts a positive slope of 0.4-2.1 ppb despite a zero Ca(NO) because of a diminishing impact of axial diffusion as flow rate increases. We conclude that axial diffusion leads to a significant backdiffusion of NO from the airways to the alveolar region that significantly impacts the partitioning of airway and alveolar contributions to exhaled NO.

Adult↗
PubMed1998

Total sputum nitrate plus nitrite is raised during acute pulmonary infection in cystic fibrosis.

Nitric oxide (NO) can be detected in exhaled gas in human subjects. It is produced by nitric oxide synthase (NOS) and is rapidly metabolized to nitrite and nitrate (NO2/NO3). Exhaled NO is reported to be elevated in patients with asthma, bronchiectasis, or upper respiratory tract infection. Recent reports have shown no increase of exhaled NO in stable cystic fibrosis (CF). We hypothesized that NOS activity is increased in patients with acute pulmonary exacerbation of CF. We therefore measured exhaled NO and sputum NO2/NO3 in three subject categories: patients with acute pulmonary exacerbation of CF, patients with stable CF, and healthy control subjects. Mean +/- SD exhaled NO was significantly higher in control subjects (8.8 +/- 4.9 ppb) than in both acute (3.8 +/- 3.9 ppb) and stable (5.0 +/- 2.5 ppb) patients. Sputum NO2/NO3 was significantly higher in acute patients (774 +/- 307 micromol/L) when compared with both stable patients (387 +/- 203 micromol/L) and control (421 +/- 261 micromol/L) subjects. Sputum NO2/NO3 did not return to normal in a subgroup of patients assessed after 2 wk of intensive antibiotic and glucocorticoid treatment. These results confirm that exhaled NO is not a useful measure of airway inflammation in CF. Elevated levels of sputum NO2/NO3 suggest that NOS is activated during acute pulmonary exacerbations of CF.

Acute Disease↗
PubMed1996

Airway nitric oxide in asthmatic children and patients with cystic fibrosis.

We evaluated the effects of asthma and cystic fibrosis on nitric oxide (NO) concentrations in the respiratory tract. NO levels in orally exhaled air and nasal gas samples were studied in 90 asthmatic patients (4-14 yrs), 67 patients with cystic fibrosis (CF) (5-32 yrs), and 68 controls (4-34 yrs). NO concentrations measured by chemiluminescene were correlated with the patient's vital capacity, forced expiratory volume in one second (FEV1) and specific airway resistance. In all groups, NO concentrations in orally-exhaled air correlated with the inhaled ambient NO (r = 0.85-0.91). At an ambient NO concentration of 0 parts per billion (ppb), asthmatic patients exhaled air with higher NO concentrations than cystic fibrosis patients and controls (8.0 +/- 6.1 ppb (n = 33); 4.9 +/- 2.6 ppb (n = 23); and 3.0 +/- 2.5 ppb (n = 37); respectively; p < 0.001). Similar results were obtained for ventilation-adjusted orally-exhaled NO. Nasal NO concentrations were lower in patients with CF (23 +/- 17 ppb) than in controls and asthmatics (96 +/- 47 and 103 +/- 64 ppb; p < 0.001). There was no relationship between nasal or oral NO and pulmonary function tests. Our results suggest that ambient NO levels influence NO concentrations in orally-exhaled air. Like adults, asthmatic children exhale more NO than their controls. Reduced nasal NO concentrations in patients with cystic fibrosis may reflect chronic epithelial cell damage or an increased mucosal barrier impeding NO diffusion into the airway.

Adolescent↗
PubMed2004

Effects of corticosteroids on noninvasive biomarkers of inflammation in asthma and chronic obstructive pulmonary disease.

Exhaled breath analysis may be used to quantify inflammation and oxidative stress in the respiratory tract, in the differential diagnosis of airway diseases, and in the monitoring of therapy. The greatest progress has been made with standardized measurement of exhaled nitric oxide (NO). Bronchial NO is increased in asthma, correlated with other markers of inflammation, and reduced by treatment with corticosteroids and antileukotrienes. Alveolar NO is increased in chronic obstructive pulmonary disease (COPD), reflecting disease severity and progression. Exhaled carbon monoxide and ethane are increased in both asthma and COPD. Increased concentrations of 8-isoprostane, hydrogen peroxide, nitrite, and nitrotyrosine are found in exhaled breath condensate from patients with inflammatory lung diseases. Increased levels of lipid mediators are also found, and the pattern depends on the nature of the disease process. Additional biomarkers are exhaled breath temperature, which is elevated in asthma and reduced in COPD, and bronchial blood flow. It is likely that smaller and more sensitive analyzers will extend the discriminatory value of exhaled breath analysis and that new techniques will become available to diagnose and monitor respiratory diseases in the family practice and home settings.

Administration, Inhalation↗
PubMedDate not supplied

Effects of low-dose hydrogen peroxide in the isolated perfused rat lung.

Isolated perfused rat lungs (IPRL) were used to determine if treatment with hydrogen peroxide would result in measurable changes in exhaled ethane during the early stages of capillary leak. Pulmonary capillary filtration coefficient, pulmonary vascular resistance, and dynamic pulmonary compliance were measured at two time points in an IPRL. Additionally, exhaled ethane was determined before and after the addition of 0.25 mM H2O2 to the perfusate in a second group of lungs. Lung wet/dry weight ratios were measured at the termination of the experiments. The ethane in the exhaled alveolar gas from IPRLs ventilated with 5%CO2/20%O2/balance N2 was quantitated using gas chromatography before and after the addition of 0.25 mM H2O2 to Krebs Ringer's 5% albumin perfusate. H2O2 (0.25 mM) caused a small but significant increase in capillary filtration coefficient from 0.0122 (+/- 0.0008) to 0.0173 (+/- 0.0013) mL/min/cm H2O/g dry lung weight (p < .05). Wet/dry lung weight ratios were increased in the H2O2-treated lungs (6.0654 +/- 0.1024 versus 5.4149 +/- 0.1143; p < .05). Exhaled ethane did not increase over the period of time hydrogen peroxide was present in the perfusate. In other experiments in closed-chested rats, 0.25 mM peroxide did not cause increased exhaled ethane, whereas 1 mM H2O2 did. This latter increase in ethane was not noted in similarly perfused open-chested rats. These data indicate that small amounts of H2O2 may increase pulmonary capillary permeability without affecting exhaled ethane measurements.

Animals↗
PubMed1991

CO2 breath tests using 14C-caffeine, 14C-methacetin and 14C-phenacetin for assessing postnatal development of monooxygenase activities in rats and marmosets.

The time course in which the activities of cytochrome P450-dependent drug-metabolizing enzymes develop during the perinatal period differs for various types of monooxygenases as well as for various animal species. Using [3-methyl14C]-, [7-methyl14C]-caffeine, [14CH3]-methacetin and [14C2H5]-phenacetin as substrates in breath tests, the developmental changes in the rates of 14CO2 formation, due to changes in the activity of monooxygenases, were studied in rats and marmoset monkeys (Callithrix jacchus). In rats a rate of 0.006% of the dose administered/min was found to be exhaled as 14CO2 in the caffeine breath tests on the 1st day of life. This value increased gradually reaching adult rates of 14CO2 exhalation after 21 days for [3-methyl14C]-caffeine and after 25 days for [7-methyl14C]-caffeine. In marmosets the rate of 14CO2 exhalation for [3-methyl14C]- and [7-methyl14C]-caffeine was also low at birth and developed gradually reaching adult values of 14CO2 exhalation within 120-200 days. In rats the capacity for dealkylation of methacetin and phenacetin developed much faster compared with caffeine: 9 days postnatally, the exhalation of 14CO2 reached adult values. Offspring of marmosets reached adult values of 14CO2 exhalation at 8 days postnatally when using [14CO2]-methacetin as substrate and at 30 days postnatally using [14C2H5]-phenacetin in the breath test. The results suggest that the monooxygenases for the N-demethylation of caffeine, the O-demethylation of methacetin and the O-deethylation are rather substrate specific in the two species studied. The breath tests used are sensitive methods for assessing the development of different monooxygenases in vivo in rats and marmosets, and they may well (using 13C-labelled substrates) be applicable for studies in children to monitor effects of certain environmental pollutants.

Acetamides↗
PubMedDate not supplied

[Significance of the sex differences of experimental animals for ethanol and acetaldehyde pharmacokinetics].

Studies of the pharmacokinetics of ethanol in the blood and exhaled air and of acetaldehyde in exhaled air in rats of different sexes have shown that in the group of normal animals, the level of endogenous ethanol and maximal blood concentration of ethanol administered in the test dose (2.2 g/kg) was higher in females than in males. The decrease of ethanol concentration in the blood and exhaled air proceeds more rapidly in males, the content of acetaldehyde in exhaled air being elevated in all the animals. In the groups of animals preferring ethanol to water, the importance of sex differences as regards the parameters under study reduces, with changes in ethanol pharmacokinetics being more distinctive in females. Unlike normal animals, the decrease of ethanol concentration in the blood and exhaled air in alcoholized rats also entails diminution of acetaldehyde content in exhaled air. After ethanol withdrawal its endogenous level considerably drops, reaching the same level in females and males.

Acetaldehyde↗
PubMed2005

Role of nitric oxide on airway microvascular permeability in patients with asthma.

BACKGROUND: We have recently emphasized that airway microcirculation has the potential to contribute to the pathophysiology of asthma. We therefore hypothesized that increased production of airway nitric oxide (NO) plays an important role in the pathogenesis of asthma through microvascular hyperpermeability. To test our hypothesis, we compared exhaled NO levels in normal subjects and asthmatic patients, and examined the contribution of airway microvascular permeability to the pathophysiology of asthma. METHODS: Inflammatory indexes in induced sputum, exhaled NO levels, and airway vascular permeability index were examined in 11 normal controls, 19 beclomethasone dipropionate (BDP)-treated asthmatics, and 20 BDP-untreated asthmatics. RESULTS: The percentage of eosinophils (% Eos) and concentration of eosinophil cationic protein (ECP) in induced sputum were significantly higher in BDP-untreated asthmatics (% Eos: 16.4 (6.5)%, p < 0.0001; ECP: 674.5 (294.2) ng/mL, p < 0.0001) than in normal controls (0.6 (0.3)%; 112.7 (65.5) ng/mL) and BDP-treated asthmatics (0.7 (0.6)%; 116.3 (72.6) ng/mL). However, exhaled NO levels were significantly higher in BDP-untreated (16.4 (6.9) ppb, p < 0.0001) and -treated (11.2 (3.5) ppb, p = 0.007) asthmatics than in normal controls (5.9 (1.8) ppb). Similarly, airway vascular permeability index was significantly higher in BDP-untreated (0.028 (0.009), p < 0.0001) and -treated (0.016 (0.006), p = 0.005) asthmatics than in normal controls (0.008 (0.003)). We found a significant correlation between exhaled NO level and airway vascular permeability index in both BDP-untreated asthmatics (r = 0.85, p < 0.0001) and -treated asthmatics (r = 0.64, p = 0.0023). Moreover, airway hyperreactivity to methacholine was also significantly correlated with exhaled NO level in BDP-untreated (r = -0.68, p = 0.003) and -treated (r = -0.49, p = 0.037) asthmatics. CONCLUSIONS: Increased production of airway NO is a key factor in the development of airway hyperresponsiveness. Interaction between airway microcirculation and NO may be a key element in disordered airway function in asthma.

Adult↗
PubMed2000

Elevation of nitrotyrosine and nitrate concentrations in cystic fibrosis sputum.

Nitric oxide (NO) is increased in the exhaled air of some patients with inflammatory lung disorders, but not in others. NO may combine with superoxide to form peroxynitrite, which lowers NO gas concentrations, increases formation of nitrate, and increases nitration of tyrosine residues on proteins. We hypothesized that superoxide released from neutrophils in the lower respiratory tract of cystic fibrosis (CF) results in increased nitrate and nitrotyrosine levels in sputum. In order to test this hypothesis, exhaled NO was collected from 5 stable adult CF subjects and from 5 nonsmoking normal controls. Consistent with previous reports, exhaled NO concentrations were not increased in CF exhaled air (22.6 +/- 1.5 ppb vs. 28.6 +/- 1.5 ppb in normals, P > 0.05). Sputum was collected from 9 adult CF subjects and the same 5 normal controls and evaluated for nitrite, nitrate, and nitrotyrosine. Nitrate and nitrotyrosine levels, but not nitrite, were significantly elevated in CF. Recently, myeloperoxidase has also been implicated as a mechanism of nitrotyrosine formation. Therefore, myeloperoxidase was measured and found to be elevated in the CF sputum (64.2 +/- 35.9 vs. 0.73 +/- 0.16 U/mL, P < 0.001), and was found to correlate with concentrations of nitrotyrosine (r = 0.87, P < 0.05). However, in vitro studies with myeloperoxidase and murine lung epithelial cells did not demonstrate a reduction of NO gas with nitrotyrosine or an increase in nitrate formation. These data demonstrate that nitrate and nitrotyrosine are elevated in the sputa of CF subjects and suggest increased production of NO in the lower respiratory tract of CF patients, despite the relatively low exhaled NO levels. Pediatr Pulmonol. 2000; 30:79-85. Published 2000 Wiley-Liss, Inc.

Adolescent↗
PubMed1993

Evaluation of biological monitoring parameters for occupational exposure to toluene.

A survey was conducted in a rotogravure printing plant with inhalatory and percutaneous exposure to toluene. Workers (n = 9) were followed for 2 consecutive days and the frequency and duration of skin contact with toluene were monitored. In order to assess percutaneous absorption an airstream helmet was worn during one day. Urine and exhaled air samples were collected simultaneously 5 times each day for toluene (urine and breath) and hippuric acid (urine). The mean (personal air sampling) exposure concentration was between 30 mg/m3 and 600 mg/m3. The best biological monitoring parameter of external exposure (without a helmet) was the concentration toluene in exhaled air 8 h after work (r = 0.99). While wearing the airstream helmet the relationship between external exposure (measured in the helmet) and concentrations in exhaled air and urine deviated from the preceding relations. This was likely the result of the high body burden and not of skin contact with toluene. Skin contact with toluene (usually by cleaning of the hands) was limited to 0-30 minutes a day, with an average of about 5 minutes. During experimental exposure (n = 6) in which the hands were washed with toluene for 5 minutes the toluene in exhaled air (max after 1040 min) clearly demonstrated skin absorption of toluene. The next morning 0.1 mg/m3 toluene was still detectable; this was less than the concentration measured the next morning in exhaled air of workers: between 0.5 and 10 mg/m3.

Adult↗
PubMed1985

Alteration of the inhibitory effect of metyrapone by reduction to metyrapol during the metabolism of methacetin in vivo in mice.

Metyrapone is known as an inhibitor of the oxidative drug metabolism in vitro. We have used the exhalation analysis as a tool to study the influence of this inhibitor on the demethylation of 14C-methacetin in vivo. In parallel we investigated the reductive metabolism of metyrapone in mice by measuring the concentrations of metyrapone and its reduced metabolite metyrapol with a HPLC-method. 50 mg of metyrapone/kg b. wt. resulted in a 90% inhibition of 14CO2 exhalation when given 2 min before the exhalation analysis was started. The prolongation of the intervals between i.p. metyrapone and substrate administration leads to a diminution of the in vivo inhibition. We found that the hepatic metyrapone concentration falls rapidly and passes the detection limit at 120 min. Transiently metyrapol reaches a maximal concentration 15 min after the application of metyrapone. The rapid reduction of metyrapone was confirmed in vitro with fresh mouse liver homogenates. The administration of metyrapol itself in vivo causes a decrease in 14CO2 exhalation, too. The 14CO2 exhalation curves after metyrapol correspond to the curves after metyrapone, when sufficient time was allowed for its reduction to metyrapol. It can be concluded that not only metyrapone itself but also its reductive metabolite metyrapol is an effective, however weaker inhibitor.

7-Alkoxycoumarin O-Dealkylase↗
PubMed2004

Quantification of recent smoking behaviour using proton transfer reaction-mass spectrometry (PTR-MS).

Smoking is the most important single risk factor in current public health. Surveillance of exposure to tobacco smoke may be accomplished using environmental monitoring or in-vivo tests for smoking biomarkers. Acetonitrile exhaled in human breath has been described as a potential marker mirroring recent smoking behavior. The aim of this study was to determine exhaled acetonitrile levels in a sample of 268 volunteers (48 smokers, 220 non-smokers) attending a local health fair. Breath specimens were collected into inert sample bags, with parallel collection of ambient air. Subsequently, all samples were analysed using proton transfer reaction-mass spectrometry (PTR-MS). Smokers had elevated levels of exhaled acetonitrile compared with non-smokers (p<0.001). Analysis using the receiver-operating-characteristic curve demonstrated that smoking can be predicted with a sensitivity of 79% and a specificity of 91%, using a cut-off concentration of 20.31 parts per billion of acetonitrile. This first field survey of exhaled acetonitrile in a large group of test persons demonstrates the feasibility of a rapid and non-invasive test for recent exposure to tobacco. We conclude that analysis of exhaled-breath acetonitrile may serve as a method of determining recent active smoking behaviour.

Acetonitriles↗
PubMed1996

Identification of N2 as a metabolite of acetylhydrazine in the rat.

In the pathogenesis of isoniazid-induced hepatic injury, cytochrome P450-dependent metabolic activation of the metabolite, acetylhydrazine (AcHz), is the crucial step. Exhalation of [14C]-carbon dioxide has previously been used to quantify indirectly this pathway. In contrast, according to the current concept of AcHz bioactivation, molecular nitrogen is produced directly, but has not yet been identified. Here, we measured [15N]-nitrogen and 14CO2 exhalation, after the administration of [15N2]-[14C]-AcHz, in rats. Laser magnetic resonance (LMR) spectroscopy, a new sensitive and specific technique for the measurement of 15N and 14N in gas samples, was used. To demonstrate the involvement of cytochrome P450, rats were treated with phenobarbital (PB) or PB+cobalt(II) chloride (CoCl2) (n = 3 in each group). Time-dependent 15N2 exhalation differed significantly between treatment groups (p < 0.001). At 240 min, cumulative exhalation of 15N was 1.92 +/- 0.43% (mean +/- SE) of the dose in the control group, 2.53 +/- 0.23% in the PB group, and 1.00 +/- 0.15% in the PB+CoCl2 group (p < 0.05 compared to controls, p < 0.01 compared to PB). Cumulative exhalation of 14CO2 in 24 h ranged from 15.1 to 21.9%, with no significant difference between treatment groups. In conclusion, N2 is a metabolite of AcHz. N2 formation reflects the cytochrome P450-mediated activation of AcHz and can be used as an index of this pathway. Generally, LMR spectroscopy is valuable for monitoring any N2-liberating process in vivo.

Animals↗
PubMed1985

Radon emanation from concrete and the influence of using flyash in cement.

In the Netherlands both Portland cement and blast furnace cement (slags from blast furnaces with about 30% Portland cement) are used for concrete. Radon exhalation measurements were carried out on concrete blocks made with these two types of cement and blocks with 15, 25 and 35% of the cement substituted by three different types of flyash. The results show that substituting part of the cement by flyash has no drastic effect on the exhalation rate. For concrete with Portland cement the exhalation rate decreases using flyash with an average radium content. With blast furnace cement a slight increase may be expected. The exhalation of concrete is greater than the sum of the exhalation values of the constituting components. The water in the pores of the concrete plays an essential role in the emanation process.

Calcium Hydroxide↗
PubMed1992

Laboratory evaluation of a filter for the control of cross-infection during pulmonary function testing.

Nosocomial transmission of respiratory pathogens is a possible complication of lung function testing. The use of a filter, placed between the patient and the spirometer equipment may be one way of preventing such nosocomial spread. This paper reports the laboratory evaluation of the efficiency of such a filter at removing bacteria from exhaled breath. Volunteers exhaled 100 normal breaths or four forced exhalations through a filter on to a blood agar plate. Bacterial counts on the agar plate were compared with recoverable bacterial counts from the filter. Total challenge from the forced exhalations ranged from 161-84,200 colony forming units. The calculated efficiency of 10 volunteers was 99.9%. For the normal breaths the challenge ranged from 0-262,000 colony forming units. There was no growth on any of the blood-agar plates. These filters appear to be highly efficient at removing exhaled bacteria.

Bacteria↗
PubMed2001

Endobronchial transfection of naked viral interleukin-10 gene in rat lung allotransplantation.

BACKGROUND: Recent studies suggest that viral interleukin-10 (vIL-10) suppresses alloimmune response in transplantation. Tissue mRNA expression of inducible nitric oxide synthase (iNOS) and exhaled nitric oxide (NO) levels have been observed to increase in lung allograft rejection. The aims of this study were to examine the feasibility of vIL-10 gene transfer into rat lung allografts and to investigate its effect on subsequent allograft rejection. METHODS: Male Lewis rats (RT1l) underwent left lung transplantation with allografts from Brown Norway rats (RT1n). The donor rats were endobronchially transfected 2 minutes before harvest with 400 microg (group I, n = 5), 600 microg (group II, n = 5), or 800 microg (group III, n = 5) of naked pCMVievIL-10. Group IV (n = 5) animals, serving as control, received 400 microg of naked pCF1-CAT. All recipients were sacrificed on postoperative day 5. Transgene expression of vIL-10 was assessed by both reverse transcriptase-polymerase chain reaction and immunohistochemistry. Allograft gas exchange, exhaled NO level, histologic rejection score, and mRNA expression of graft cyokines were also assessed. RESULTS: Transgene expression of lung graft vIL-10 was detected by both reverse transcriptase-polymerase chain reaction and immunohistochemistry. The iNOS mRNA expression in groups I, II, and III was significantly lower than that of group IV (p < 0.05, analysis of variance). Exhaled NO levels in groups I, II, and III were significantly lower than in group IV (p < 0.01, analysis of variance). There was no significant difference between groups with respect to gas exchange, peak airway pressure, or histologic rejection score. CONCLUSIONS: It appears that endobronchial transfection of naked vIL-10 plasmid in a rat lung allotransplant model is feasible and suppresses lung iNOS mRNA expression and exhaled NO levels. An association between iNOS upregulation and high exhaled NO levels in lung allograft resection was also noted.

Analysis of Variance↗