J Appl Physiol 100: 672-678, 2006.
First published October 6, 2005; doi:10.1152/japplphysiol.00274.2005
8750-7587/06 $8.00
Vasoactive mediators and pulmonary hypertension after cigarette smoke exposure in the guinea pig
Joanne L. Wright,
Hsin Tai, and
Andrew Churg
Department of Pathology, University of British Columbia, Vancouver, British Columbia, Canada
Submitted 8 March 2005
; accepted in final form 20 September 2005
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ABSTRACT
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The pathogenesis of pulmonary hypertension in patients with chronic obstructive pulmonary disease is not understood. We have previously shown increased levels of mediators that control vasoconstriction (endothelin-1), vascular cell proliferation (endothelin-1 and vascular endothelial growth factor), and vasodilation (endothelial nitric oxide synthase) in the intrapulmonary arteries of animals exposed to cigarette smoke. To determine whether these mediators could be implicated in the structural remodeling of the arterial vasculature and increased pulmonary arterial pressure caused by chronic cigarette smoke exposure, guinea pigs were exposed to daily cigarette smoke for 6 mo. Pulmonary arterial pressures were measured. Intrapulmonary artery structure was analyzed by morphometry, artery mediator protein expression by immunohistochemistry, and artery mediator gene expression by laser capture microdissection and real-time RT-PCR. We found that the smoke-exposed animals developed increases in pulmonary arterial pressure and increased muscularization of the small pulmonary arteries. Gene expression and protein levels of all three mediators were increased, and pulmonary arterial pressure correlated both with the levels of mediator production and with the degree of arterial muscularization. We conclude that chronic smoke exposure produces increased vasoactive mediator expression in the small intrapulmonary arteries and that these mediators are associated with vascular remodeling as well as increased pulmonary arterial pressure. These findings support the idea that hypertension in chronic obstructive pulmonary disease is a result of direct cigarette smoke-mediated effects on the vasculature and suggest that interference with endothelin and VEGF production and activity or augmentation of nitric oxide levels may be beneficial.
endothelin; nitric oxide synthase; vascular endothelial growth factor
SOME CIGARETTE SMOKERS WHO have chronic obstructive lung disease (COPD) have been shown to develop small but progressive increases in pulmonary arterial pressure (16, 31). This represents an important prognostic variable (5, 35, 39, 40) because an increase in mean pulmonary arterial pressure of 10 mmHg is associated with a greater than fourfold increase in mortality in patients with COPD (3).
The pathogenesis of cigarette smoke-induced pulmonary hypertension is unclear. The traditional view, namely that pulmonary hypertension in patients with COPD is secondary to emphysematous destruction of the vascular bed and/or hypoxia, is not supported by current studies (5, 31). Using an animal model of cigarette smoke exposure, we have investigated the alternate hypothesis that smoke acts directly on the vasculature to affect production of mediators that control vasoconstriction, vasodilation, and muscle cell proliferation, a process that has been observed in other forms of pulmonary hypertension (22, 24, 32). In previous studies, our laboratory found upregulation of gene expression and protein production of the vasoconstrictive and/or proliferative peptide, endothelin, the vascular cell proliferative agent, vascular endothelial growth factor (VEGF), and endothelial nitric oxide synthase (eNOS, otherwise known as NOS III), which produces the vasodilator nitric oxide (42, 44, 45) in the intrapulmonary arteries of guinea pigs after either a single smoke exposure or in animals exposed to smoke for up to 12 wk. These mediators were increased in both the muscularized and partially muscularized pulmonary arteries (44).
Our group has previously shown that Hartley strain guinea pigs develop increases in pulmonary arterial pressure after long-term smoke exposure, with both structural and dynamic alteration of the vascular bed (41). One particularly useful aspect of this outbred strain is that, after smoke exposure, increases in arterial pressure are quite variable, a phenomenon that mimics human disease. Using the guinea pig model, we show here for the first time that the level of pulmonary arterial pressure correlates with the amount of muscularization of the small intrapulmonary arteries and the vascular gene expression and protein levels of these mediators.
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METHODS
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The research protocol was approved by the University of British Columbia.
Smoke exposure, vascular physiology, and tissue collection.
We exposed four male Hartley strain guinea pigs to the whole smoke of seven 2R1 research cigarettes (University of Kentucky) 5 days/wk for 6 mo using our previously published exposure protocol (33), with an additional group of three guinea pigs exposed to room air as a control population. At 6 mo, the animals were anesthetized using urethane anesthesia (0.5 g/kg ip) and intubated, and a catheter was placed into the pulmonary artery via the jugular vein (41). After a period of stabilization on the ventilator, with animals breathing room air, pulmonary arterial pressure was measured, and the animal was killed by anesthesia overdose followed by exsanguination. The lungs were removed and inflated with cold 100% ethanol. This type of fixation is needed to preserve RNA in guinea pigs, a species with very high levels of endogenous ribonucleases. Slices of lung were embedded in paraffin, and multiple 5-µm-thick sections were cut onto diethyl pyrocarbonate-treated (Sigma-Aldrich, Oakville, ON, Canada) water and collected on cleaned slides. One section was deparaffinized and stained with hematoxylin and eosin to serve as a dissection guide. The remaining sections were deparaffinized and stained by using the Arcturus (Arcturus, Mountain View, CA) stain and protocol for subsequent laser capture microdissection.
Laser capture microdissection, mRNA extraction, and reverse transcription reaction.
We utilized the Arcturus Pixcell II (Arcturus) laser capture microdissection apparatus and separately collected the muscularized vessels adjacent to the membranous or respiratory bronchioles and the small, partially muscularized vessels adjacent to the alveolar ducts onto laser capture microdissection caps as per our previous protocol (44). The caps were placed on Eppendorf (Mississauga, ON, Canada) 500-µl tubes and stored at –80°C until the RNA extraction and isolation procedure. We used the PicoPureJ RNA Isolation kit (Arcturus) for RNA extraction and isolation as described by us previously (44), combining all samples from an individual animal as one data point for each of the respective sites. First-strand cDNA was synthesized by using superscript J II RNase H Reverse Transcriptase (Invitrogen, Burlington, ON, Canada), and real-time RT-PCR reactions were carried out in LightCycler glass capillaries using a reaction mixture with LightCycler-FastStart DNA Master SYBR Green I (Roche, Mannheim, Germany). Each set of PCR reactions included water as a negative control and five dilutions of standards that were created by cloning part of the transcript of interest into a cloning vector (Invitrogen, Carlsbad, CA). 
-Actin was used as a housekeeping gene.
Primer sequences.
where iNOS is inducible nitric oxide synthase.
Immunohistochemistry and morphometric analysis.
Muscularization of the small vessels adjacent to the alveolar ducts was determined by immunohistochemical staining with monoclonal mouse anti-human 
-smooth muscle actin (catalog M0851, DAKO, Mississauga, ON, diluted 1:200) using standard immunohistochemical procedures with appropriate positive and negative controls. In each animal, we examined 25 vessels adjacent to alveolar ducts identified by random light microscopic fields using a x20 objective and x10 eyepieces. Each vessel was categorized into quartiles, depending on the percentage of the vessel circumference surrounded by muscle cells. To develop a final animal score, we then weighted each quartile by 1–4, respectively, and summed the values.
Immunohistochemical evaluation of VEGF, endothelin, and eNOS was carried out as previously described (44), using standard technique with appropriate controls. The slides were coded to prevent bias. Anti-eNOS and anti-VEGF were obtained from R&D Systems (Minneapolis, MN) and diluted to 10 µg/ml and 15 µg/ml, respectively; anti-endothelin was obtained from Biodesign (Saco, ME) and diluted 1:100. To evaluate staining, we utilized a grading system based on extent and intensity of staining reaction compared with background. Each vessel of the appropriate size in the histological section was examined and assigned a grade. Grade 0 was defined as no staining, whereas grade 3 was defined as intense and diffuse vessel staining. A final animal grade was obtained by summation of all grades and expressed as a percentage of the maximum possible grade for that number of vessels.
Data analysis and statistics.
By using the crossing point curves values generated by the LightCycler and the standard curves, relative concentrations of each RNA of interest were determined and corrected for loading with the corresponding actin value. We compared the mRNA data from control animals and smoke-exposed animals by analysis of variance. Because the immunohistochemical staining data were not normally distributed, relationships between these data and pulmonary arterial pressure or the mRNA levels were determined by the Spearman rank correlation test.
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RESULTS
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The pulmonary arterial pressure (Ppa) in the smoke-exposed guinea pigs was significantly increased compared with that of the control animals [smoke exposed (mean ± SD) 9.8 ± 1.3 vs. control 7.0 ± 1.2 cmH2O, P = 0.04]. There was considerable variation in Ppa in the smoke-exposed animals, with a range of 8.7 to 11.7 cmH2O, compared with 5.7 to 7.7 in the control animals. The muscularization score index of the partially muscularized arteries (Fig. 1) was (mean ± SD) 72 ± 5 in the smoke-exposed animals compared with 54 ± 5 in the control animals (P = 0.005).
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Fig. 1. Muscularization index of the usually partially muscularized vessels (PMV) adjacent to the alveolar ducts. Values are means ± SD. Smoke exposure is associated with a significant increase in the degree of muscularization of these vessels (*P = 0.005).
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Figure 2 shows the relative levels of gene expression for the animals in each group separated into partially muscularized and muscularized vessels. For ease of interpretation and to allow for visualization of the range of the data points in each group, the data are presented with the mean control animal level for each time, vessel size, and gene normalized to a value of 1.0 and other values adjusted accordingly. However, all statistical analyses were performed from the raw data sets. The controls showed relatively little animal-to-animal variation in gene expression levels; however, gene expression levels for all three mediators were significantly, but variably, increased in the smoke-exposed animals. In the partially muscularized vessels from the smoke-exposed animals, endothelin was increased on average 
10-fold, VEGF was increased 12-fold, and eNOS was increased 4-fold over control levels. In the muscularized arteries, endothelin and VEGF were increased about eightfold, and eNOS was increased fourfold compared with the levels in the control animals. There was no difference in the level of iNOS between control and smoke-exposed animals.
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Fig. 2. Gene expression levels of endothelin (A), VEGF (B), endothelial nitric oxide synthase (eNOS; C) and inducible nitric oxide synthase (iNOS; D) in PMV and muscularized (MV) small intrapulmonary arteries isolated by laser capture microdissection. Smoke causes a significant upregulation of endothelin, VEGF, and eNOS compared with control, whereas there is no change in levels of iNOS mRNA. Bars are means ± SD. *Significantly greater than control, P < 0.05 or less.
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Figure 3 shows the data from the immunohistochemical score analyses, and Fig. 4 illustrates representative immunohistochemistry images for the various mediators. There was a small but consistent increase in the staining score for eNOS in both the partially muscularized and muscularized vessels. Endothelin scores were approximately tripled in the partially muscularized vessels and doubled in the muscularized vessels. Staining scores for VEGF were approximately doubled in both vessel sizes. Table 1 shows that gene expression levels of endothelin and eNOS correlated with the muscularization score and that even stronger correlations were found for immunohistochemically graded protein levels of all three mediators and muscularization scores.
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Fig. 3. Graded immunohistochemical levels of endothelin (A), VEGF (B), and eNOS (C) protein in PMV and MV small intrapulmonary arteries. Smoke causes a significant upregulation of all 3 mediators compared with control. Bars are means ± SD. *Significantly greater than control, P < 0.05 or less.
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Fig. 4. Photographic panel illustrating immunohistochemical staining for endothelin (A, control; B, smoke exposed), VEGF (C, control; D, smoke exposed), eNOS (E, control; F, smoke exposed), and smooth muscle actin (G, control; H, smoke exposed).
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Table 2 documents the correlations between Ppa and the levels of mRNA and immunoreactive protein. There were positive correlations with the gene expression levels of all mediators in the muscularized vessels and levels of both VEGF and eNOS in the partially muscularized vessels; correlations with endothelin approached but did not achieve significance in the muscularized arteries. Correlations between Ppa and immunoreactive protein grade scores were significant for all three mediators. The Ppa also correlated with the muscularization score in the partially muscularized vessels (R = 0.74, P = 0.03).
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DISCUSSION
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In this study we have shown that chronic exposure to cigarette smoke produces pulmonary hypertension in guinea pigs and that the level of Ppa elevation correlates with increases in production of vasoactive mediators as well as increases in muscularization in the small, normally partially muscularized, vessels. It is important to recognize that in guinea pigs with chronic cigarette smoke exposure (41, 43), as in humans with COPD (16), the increases in Ppa tend to be small. However, because even these small increases in Ppa appear to be a separate and significant factor in morbidity and mortality, it is useful to understand the factors that may be responsible for the vascular alterations.
In previous studies (44, 45), our laboratory has shown that cigarette smoke can induce rapid (within a few hours) gene upregulation of the vasoactive mediators endothelin, VEGF, and eNOS in small intrapulmonary arteries. Gene upregulation was not transient but persisted with smoke exposures of up to 3 mo (44) and was associated with increases in immunoreactive protein in the muscularized and partially muscularized vessels during this time. The present study shows that continued upregulation is present for as long as 6 mo of smoke exposure. Most importantly, it demonstrates that there are significant correlations between the Ppa and mRNA and protein levels of these mediators in both the muscularized and partially muscularized vessels. Furthermore, correlations are present between the Ppa and the degree of vascular remodeling of the partially muscularized arteries.
It is now known that endothelial cells have the ability to modulate their own function through the synthesis and release of a number of bioactive substances, including endothelin, VEGF, and nitric oxide, which act on the underlying smooth muscle cells and also act on the endothelial cells in a feedback mechanism (reviewed in Ref. 13). However, the relationships among these mediators are complex. It appears that there is an intimate association between endothelin and nitric oxide, with each modulating the production of the other in an autocrine fashion and the actions of the other in a paracrine fashion (13). Endothelin stimulates production and release of nitric oxide (46), and nitric oxide production dissociates endothelin from its receptors and interferes with the pathway for calcium mobilization (27), thus inhibiting end responses to endothelin (9). Nitric oxide decreases expression of both VEGF and VEGF-receptor (36), similar to its effect on endothelin (19). Conversely, VEGF appears to augment nitric oxide release from the endothelium (30). Finally, VEGF has been found to activate eNOS through phosphorylation at serine 1177 (23).
These complicated relationships help to explain our results. Intuitively, one would expect, given the presence of vascular remodeling leading to thicker walled vessels with more muscle (see below) and increased Ppa (lack of vasodilatation) in the smokers, that endothelin and VEGF production should be upregulated, but eNOS should not. We suggest that, in our model, upregulation of endothelin and VEGF drives increased production of eNOS as well but that the levels and/or activity of eNOS in the smokers are insufficient (see below) to compensate for the proliferative and constrictive effects of increased endothelin and VEGF. Thus the levels of eNOS gene expression and protein probably serve here as surrogate markers of endothelin and VEGF activity, hence their correlation with vascular remodeling and Ppa. This explanation is supported by the close correlations in mRNA levels between eNOS and both VEGF (muscularized vessels R = 0.89, P = 0.003, partially muscularized vessels R = 0.82, P = 0.01) and endothelin (muscularized vessels R = 0.96, P = 0.001, partially muscularized vessels R = 0.75, P = 0.03).
Cigarette smoke contains large amounts of nitric oxide, which appears to decrease exhaled nitric oxide through downregulation of NOS isoforms in the epithelium (17); our previous work, however, demonstrated acute upregulation of eNOS and iNOS in airway epithelium of rats exposed to cigarette smoke. In fact, the exact relationship of eNOS production and activity in animals or humans exposed to cigarette smoke is debated and certainly complicated. For example, Su and colleagues (33a), using a pulmonary artery endothelial cell culture model, found that smoke reduced eNOS activity by a reduction of protein levels and mRNA, and Barbera et al. (1) have shown decreased immunohistochemical expression of eNOS in the pulmonary arteries of smokers. However, Tuder et al. (37) found increased nitric oxide production by cultured epithelial cells after exposure to cigarette smoke condensate, and our laboratory (42) has found increased gene expression of eNOS by in situ hybridization in the pulmonary endothelium of rats exposed to smoke, as well as evidence of upregulated gene expression in isolated intrapulmonary arteries in rats and guinea pigs exposed to smoke (44, 45). Smoke also exerts a number of other effects on eNOS production. TNF-, which is increased in the sputum of human smokers with COPD (15) and in the plasma of animal models of COPD (2), downregulates eNOS protein levels by destabilizing eNOS mRNA (21). Smoke also inhibits production of tetrahydrobiopterin (10), a required cofactor for eNOS activity. In addition, the endothelial response to nitric oxide is attenuated by increased levels of endothelin (14).
Nitric oxide could also be produced by increases in iNOS. In rats, our laboratory has previously found (42) that smoke transiently upregulates gene expression of iNOS, although it does not increase immunohistochemically detectable protein, and that iNOS gene expression increases do not persist over the long term. The present study indicates that long-term smoke exposure also does not alter iNOS gene expression in the guinea pig over the long term and implies that there is considerable selectivity to the genes that are upregulated in the vessels by cigarette smoke.
In theory, nitric oxide present in smoke should itself be able to act as a vasodilator; however, it is likely that the bioavailability of either endogenously or exogenously produced nitric oxide can be impaired by other reactive oxygen species present in smoke, because superoxide anion and nitric oxide rapidly combine to form the highly reactive oxidant peroxynitrite (25).
Overall, these considerations suggest that eNOS protein production would not have a one-to-one relationship to function (10), thus helping to explain the impaired endothelium relaxation found in the pulmonary arteries of patients with COPD (4).
Our data imply that all three mediators are involved in cigarette smoke-induced vascular remodeling. Endothelin production or release is stimulated by vascular stress, airway inflammation, and oxidants (7, 12), and cigarette smoke is a highly concentrated source of oxidants (26). Cigarette smoke extract has been demonstrated to induce increased expression of endothelin in cultured pulmonary artery cells (20), and studies of patients with COPD have demonstrated an increased plasma level of endothelin (28, 34). As was true in the present experiment, increased expression of endothelin has been found in the lungs of patients with pulmonary hypertension (8) from a variety of etiologies, including COPD. Endothelin increases reactive oxygen species production in arterial smooth muscle cells and is able to decrease eNOS expression through a hydrogen peroxide-based mechanism (38). Increased oxidant stress is known to induce increased synthesis of VEGF from vascular smooth muscle cells, with subsequent enhancement of atherogenic vascular remodeling (18).
The importance of adequate levels of eNOS in preventing vascular remodeling has been demonstrated by Fagan et al. (6), who showed that eNOS null mice develop marked hypoxia-induced pulmonary hypertension, with a pronounced increase in the number of muscularized small arteries. These authors compared homozygous knockout to heterozygous knockout mice and found that at least 50% of wild-type NOS expression was required to maintain normal pulmonary vascular tone.
Increased expression of VEGF has been identified in the medial smooth muscle of arteries in the lungs of patients with pulmonary hypertension secondary to a variety of etiologies (11), but there are few data regarding the role of VEGF in remodeling of the pulmonary vasculature in COPD. Santos and colleagues (29) reported immunohistochemically increased VEGF protein in the pulmonary arteries of smokers with and without COPD. On the other hand, they (29) failed to find alterations of VEGF mRNA levels between smokers with and without COPD, but their measurements were made on bulk lung samples, and thus subtle differences may not have been identified.
In summary, the present study has demonstrated a positive relationship between levels of the vasoactive mediators endothelin, eNOS, and VEGF, and Ppa. To our knowledge, this is the first time such a relationship has been shown. Muscularization of the small pulmonary arteries is also positively related to these mediators, suggesting that they probably have a causative role in structural remodeling. Whether the increases in Ppa result from dynamic mediator activity or from mediator-induced vascular remodeling is not clear, and both processes probably play a role. These results must be extrapolated from laboratory animals to humans with caution. However, our study suggests that pulmonary hypertension associated with cigarette smoke is a direct consequence of the response of the vessels to the smoke and that interference with endothelin and VEGF production, or augmentation of nitric oxide production, might be beneficial in smokers with pulmonary hypertension.
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GRANTS
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This research was supported by Grant MOP62693 from the Canadian Institutes of Health Research.
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DISCLOSURES
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J. L. Wright and A. Churg have received funds from AstraZeneca to examine animal models of emphysema and test the effectiveness of various compounds under development.
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FOOTNOTES
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Address for reprint requests and other correspondence: J. L. Wright, Dept. of Pathology, University of British Columbia, 2211 Wesbrook Mall, Vancouver, BC, Canada V6T 2B5 (email: jlwright{at}interchange.ubc.ca)
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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REFERENCES
|
|---|
- Barbera JA, Peinado VI, Santos S, Ramirez J, Roca J, and Rodriguez-Roisin R. Reduced expression of endothelial nitric oxide synthase in pulmonary arteries of smokers. Am Rev Respir Dis 164: 709–713, 2001.
- Churg A, Dai J, Tai H, Xie C, and Wright JL. Tumor necrosis factor- is central to acute cigarette smoke induced inflammation and connective tissue breakdown. Am J Respir Crit Care Med 166: 849–854, 2002.[Abstract/Free Full Text]
- Cooper R, Ghali J, Simmons BE, and Castaner A. Elevated pulmonary artery pressure. Chest 99: 112–120, 1991.[CrossRef][ISI][Medline]
- Dinh-Xuan AT, Higenbottam TW, Clelland CA, Pepke-Zaba J, Cremona G, Butt AY, Large SR, Wells FC, and Wallwork J. Impairment of endothelium-dependent pulmonary-artery relaxation in chronic obstructive lung disease. N Engl J Med 324: 1539–1547, 1991.[Abstract]
- Doi M, Nakano K, Hiramoto T, and Kohno N. Significance of pulmonary artery pressure in emphysema patients with mild-to-moderate hypoxemia. Respir Med 97: 915–920, 2003.[CrossRef][ISI][Medline]
- Fagan KA, Fouty BW, Tyler RC, Morris KG, Hepler LK, Sato K, LeCras TD, Abman SH, Weinberger HD, Huang PL, McMurtry IF, and Rodman DM. The pulmonary circulation of homozygous or heterozygous eNOS-null mice is hyperresponsive to mild hypoxia. J Clin Invest 103: 291–299, 1999.[ISI][Medline]
- Finsnes F, Christensen G, Lyberg T, Sejersted OM, and Skjonsberg OH. Increased synthesis and release of endothelin-1 during the initial phase of airway inflammation. Am J Respir Crit Care Med 158: 1600–1606, 1998.[Abstract/Free Full Text]
- Giaid A, Yanagisawa M, Langleben D, Michel RP, Levy R, Shennib H, Kimura S, Masaki T, Duguid WP, and Stewart DJ. Expression of endothelin-1 in the lungs of patients with pulmonary hypertension. N Engl J Med 328: 1732–1739, 1993.[Abstract/Free Full Text]
- Goligorsky MS, Tsukahara H, Magazine H, Andersen TT, Malik AB, and Bahou WF. Termination of endothelin signaling: role of nitric oxide. J Cell Physiol 158: 485–494, 1994.[CrossRef][ISI][Medline]
- Heitzer T, Brockoff C, Mayer B, Warnholtz A, Mollnau H, Henne S, Meinertz T, and Munzel T. Tetrahydrobiopterin improves endothelium-dependent vasodilation in chronic smokers: evidence for a dysfunctional nitric oxide synthase. Circ Res 86: E36–E41, 2000.[ISI][Medline]
- Hirose S, Hosada Y, Furuya S, Otsuki T, and Ikeda E. Expression of vascular endothelial growth factor and its receptors correlates closely with formation of the plexiform lesion in human pulmonary hypertension. Pathol Int 50: 472–479, 2000.[CrossRef][ISI][Medline]
- Hughes AK, Stricklett PK, Padilla E, and Kohan DE. Effect of reactive oxygen species on endothelin-1 production by human mesangial cells. Kidney Int 49: 181–189, 1996.[ISI][Medline]
- Hunley TE, Iwasaki S, Homma T, and Kon V. Nitric oxide and endothelin in pathophysiological settings. Pediatr Nephrol 9: 236–244, 1995.
- Jernigan NL, Walker BR, and Resta TC. Endothelium-derived reactive oxygen species and endothelin-1 attenuate NO-dependent pulmonary vasodilation following chronic hypoxia. Am J Physiol Lung Cell Mol Physiol 287: L801–L808, 2004.[Abstract/Free Full Text]
- Keatings VM, Collins PD, Scott DM, and Barnes PJ. Differences in interleukin-8 and tumor necrosis factor-alpha in induced sputum from patients with chronic obstructive pulmonary disease or asthma. Am J Respir Crit Care Med 153: 530–534, 1996.[Abstract]
- Kessler R, Faller M, Weitzenblum E, Chaquat A, Aykut A, Ducolone A, Ehrhart M, and Oswald-Mammosser M. "Natural history" of pulmonary hypertension in a series of 131 patients with chronic obstructive lung disease. Am J Respir Crit Care Med 164: 219–224, 2001.[Abstract/Free Full Text]
- Kharitonov SA, Robbins RA, Yates D, Keatings V, and Barnes PJ. Acute and chronic effects of cigarette smoking on exhaled nitric oxide. Am J Respir Crit Care Med 152: 609–612, 1995.[Abstract]
- Khatri JJ, Johnson C, Magid R, Lessner SM, Laude KM, Kikalov SI, Harrison DG, Sung HJ, Rong Y, and Galis ZS. Vascular oxidant stress enhances progression and angiogenesis of experimental atheroma. Circulation 109: 520–525, 2004.[Abstract/Free Full Text]
- Kourembanas S, McQuillan LP, Leung GK, and Faller DV. Nitric oxide regulates the expression of vasoconstrictors and growth factors by vascular endothelium under both normoxia and hypoxia. J Clin Invest 92: 99–104, 1993.[ISI][Medline]
- Lee SD, Lee DS, Chun YG, Shim TS, Lim CM, Koh Y, Kim WS, Kim DS, and Kim WD. Cigarette smoke extract induces endothelin-1 via protein kinase C in pulmonary artery endothelial cells. Am J Physiol Lung Cell Mol Physiol 281: L403–L411, 2001.[Abstract/Free Full Text]
- Li H, Wallerath T, and Forstermann U. Physiological mechanisms regulating the expression of endothelial-type NO synthase. Nitric Oxide 7: 132–147, 2002.[CrossRef][ISI][Medline]
- Louzier V, Raffestin B, Leroux A, Branellee D, Caillaud JM, Levame M, Eddahibi S, and Adnot S. Role of VEGF-B in the lung during development of chronic hypoxic pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 284: L926–L937, 2003.[Abstract/Free Full Text]
- Musicki B, Palese MA, Crone JK, and Burnett AL. Phosphorylated endothelial nitric oxide synthase mediates vascular endothelial growth factor-induced penile erection. Biol Reprod 70: 282–289, 2004.[Abstract/Free Full Text]
- Pfeifer M, Blumberg FC, Wolf K, Sandner P, Elsner D, Riegger GAJ, and Kurtz A. Vascular remodeling and growth factor gene expression in the rat lung during hypoxia. Respir Physiol 111: 201–212, 1998.[CrossRef][ISI][Medline]
- Pryor WA and Stone K. Oxidants in cigarette smoke. Radicals, hydrogen peroxide, peroxynitrate, and peroxynitrite. Ann NY Acad Sci 686: 12–28, 1993.[ISI][Medline]
- Rahman I and MacNee W. Role of oxidants/antioxidants in smoking-induced lung diseases. Free Radic Biol Med 21: 669–681, 1996.[CrossRef][ISI][Medline]
- Redmond EM, Cahill PA, Hodges R, Zhang S, and Sitzmann JV. Regulation of endothelin receptors by nitric oxide in cultured rat vascular smooth muscle cells. J Cell Physiol 166: 469–479, 1996.[CrossRef][ISI][Medline]
- Roland M, Bhowmik A, Sapsford RJ, Seemungal TAR, Jeffries DJ, Warner TD, and Wedzicha JA. Sputum and plasma endothelin-1 levels in exacerbations of chronic obstructive pulmonary disease. Thorax 56: 30–35, 2001.[Abstract/Free Full Text]
- Santos S, Peinado VI, Ramirez J, Morales-Blanhir J, Bastos R, Roca J, Rodriguez-Roisin R, and Barbera JA. Enhanced expression of vascular endothelial growth factor in pulmonary arteries of smokers and patients with moderate chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1250: 1256–2003.
- Scalia R, Booth G, and Lefer DJ. Vascular endothelial growth factor attenuates leukocyte-endothelium interaction during acute endothelial dysfunction: essential role of endothelium-derived nitric oxide. FASEB J 13: 1039–1046, 1999.[Abstract/Free Full Text]
- Scharf SM, Iqbal M, Keller C, Criner G, Lee S, and Fessler HE. Hemodynamic characterization of patients with severe emphysema. Am J Respir Crit Care Med 166: 314–322, 2002.[Abstract/Free Full Text]
- Schermuly RT, Kreisselmeier KP, Ghofrani HA, Yilmaz H, Butrous G, Ermert L, Ermert M, Weissmann N, Rose F, Guenther A, Walmrath D, Seeger W, and Grimminger F. Chronic sildenafil treatment inhibits monocrotaline-induced pulmonary hypertension in rats. Am J Respir Crit Care Med 169: 39–45, 2004.[Abstract/Free Full Text]
- Sekhon HS, Wright JL, and Churg A. Cigarette smoke causes rapid cell proliferation in small airways and associated pulmonary arteries. Am J Physiol Lung Cell Mol Physiol 267: L557–L563, 1994.[Abstract/Free Full Text]
- Su Y, Han W, Giraldo C, Li YD, and Block ER. Effect of cigarette smoke extract on nitric oxide synthase in pulmonary artery endothelial cells. Am J Respir Cell Mol Biol 19: 819–825, 1998.[Abstract/Free Full Text]
- Trakada G, Marangos M, and Spiropoulos K. Mechanisms of endothelin-1 elevation in chronic obstructive pulmonary disease patients with nocturnal oxyhemoglobin desaturation. Respiration 68: 134–139, 2001.[CrossRef][ISI][Medline]
- Traver GA, Cline MG, and Burrows B. Predictors of mortality in chronic obstructive pulmonary disease. Am Rev Respir Dis 119: 895–902, 1979.[ISI][Medline]
- Tuder RM, Flook BE, and Voelkel NF. Increased gene expression for VEGF and VEGF receptors KDR/Klk and Flt in lungs exposed to acute or to chronic hypoxia. Modulation of gene expression by nitric oxide. J Clin Invest 95: 1798–1807, 1995.[ISI][Medline]
- Tuder RM, Wood K, Taraseviciene L, Flores SC, and Voelkel NF. Cigarette smoke extract decreases the expression of vascular endothelial growth factor by cultured cells and triggers apoptosis of pulmonary endothelial cells. Chest 117: 241S-242S, 2000.[CrossRef][ISI][Medline]
- Wedgwood S and Black SM. Endothelin-1 decreases endothelial NOS expression and activity through ETA receptor-mediated generation of hydrogen peroxide. Am J Physiol Lung Cell Mol Physiol 288: L480–L487, 2005.[Abstract/Free Full Text]
- Weitzenblum E, Hirth C, Ducolone A, Mirhom R, Rasaholinjanahary J, and Ehrhart M. Prognostic value of pulmonary artery pressure in chronic obstructive pulmonary disease. Thorax 36: 752–758, 1981.[Abstract]
- Weitzenblum E, Hirth C, Parini JP, Rasaholinjanahary J, and Oulet P. Clinical, functional and pulmonary hemodynamic course of patients with chronic obstructive pulmonary disease followed-up over 3 years. Respiration 36: 1–9, 1978.[ISI][Medline]
- Wright JL. The relationship of increased pulmonary artery pressure and airflow obstruction to emphysema. J Appl Physiol 74: 1320–1324, 1993.[Abstract/Free Full Text]
- Wright JL, Dai J, Zay K, Price K, Gilks B, and Churg A. Effects of cigarette smoke on nitric oxide synthase expression in the rat lung. Lab Invest 79: 975–983, 1999.[ISI][Medline]
- Wright JL, Lawson L, Pare PD, Hooper RO, Peretz DI, Nelems JM, Schulzer M, and Hogg JC. The structure and function of the pulmonary vasculature in mild chronic obstructive pulmonary disease. Am Rev Respir Dis 128: 702–707, 1983.[ISI][Medline]
- Wright JL, Tai H, and Churg A. Cigarette smoke induces persisting increases of vasoactive mediators in pulmonary arteries. Am J Respir Cell Mol Biol 31: 501–509, 2004.[Abstract/Free Full Text]
- Wright JL, Tai H, Dai J, and Churg A. Cigarette smoke induces rapid changes in gene expression in pulmonary arteries. Lab Invest 82: 1391–1398, 2002.[ISI][Medline]
- Zellers TM, McCormick J, and Wu Y. Interaction among ET-1, endothelium-derived nitric oxide, and prostacyclin in pulmonary arteries and veins. Am J Physiol Heart Circ Physiol 267: H139–H147, 1994.[Abstract/Free Full Text]
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