(Circulation. 2001;103:2014.)
© 2001 American Heart Association, Inc.
Basic Science Reports |
Deficiency of Urokinase-Type Plasminogen Activator–Mediated Plasmin Generation Impairs Vascular Remodeling During Hypoxia-Induced Pulmonary Hypertension in Mice
From the Center for Transgene Technology and Gene Therapy, Flanders Interuniversity Institute for Biotechnology, University of Leuven, Belgium (M.L., L.M., A.B., D.C., P.C.); the Department of Vascular Medicine and Internal Medicine, Academic Medical Center, University of Amsterdam, The Netherlands (M.L.); and the Department of Pediatrics, Cell Biology, and Medicine, Washington University School of Medicine, St Louis Children’s Hospital, St Louis, Mo (S.D.S.).
Correspondence to Peter Carmeliet, MD, PhD, Center for Transgene Technology and Gene Therapy, Flanders Interuniversity Institute for Biotechnology, Campus Gasthuisberg, KU Leuven, Herestraat 49, B-3000 Leuven, Belgium. E-mail peter.carmeliet{at}med.kuleuven.ac.be
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Abstract |
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Background—Chronic hypoxia results in the development of pulmonary hypertension and subsequent right heart failure. A role of the plasminogen system in the pathogenesis of pulmonary hypertension and pulmonary vascular remodeling has been suggested.
Methods and Results—Mice with targeted deficiency of the gene encoding tissue-type plasminogen activator (t-PA-/-), urokinase-type plasminogen activator (u-PA-/-), u-PA receptor (u-PAR-/-), or plasminogen (plg-/-) were subjected to hypoxic conditions. Hypoxia caused a significant 2.5-fold rise in right ventricular pressure in wild-type mice. Deficiency of u-PA or plasminogen prevented this increase in right ventricular pressure, t-PA-/- mice showed changes that were fully comparable with wild-type mice, and u-PAR-/- mice showed a partial response. Hypoxia induced an increase in smooth muscle cells within pulmonary arterial walls and a vascular rarefaction in the lungs of wild-type but not of u-PA-/- or plg-/- mice. Elastic lamina fragmentation, observed in hypoxic wild-type but not in u-PA or plasminogen-deficient mice, suggested that proliferation of vascular smooth muscle cells was dependent on u-PA–mediated elastic membrane degradation. Hypoxia-induced right ventricular remodeling in wild-type mice, characterized by cardiomyocyte hypertrophy and increased collagen contents, was not seen in u-PA-/- and plg-/- mice.
Conclusions—Loss of the u-PA or plasminogen gene protects against the development of hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. These observations point to an essential role of u-PA–mediated plasmin generation in the adaptive response to chronic hypoxia and the occurrence of hypoxic pulmonary vascular disease.
Key Words: plasminogen • plasminogen activators • pulmonary heart disease • vasculature • remodeling
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Introduction |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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Hypoxia is one of the most potent stimuli for the formation of new blood vessels (angiogenesis), and it mediates vasodilation of vessels, thereby improving tissue perfusion.1 Lung vessels, however, react to acute hypoxia with constriction rather than dilation, in part through upregulation of vasoactive substances.2 3 4 Furthermore, hypoxia causes pulmonary vascular cells to proliferate in contrast to the usual growth-suppressive effect of hypoxia on many other cell types.2 3 4 5 6 On prolonged hypoxia, pulmonary vessels undergo significant structural changes involving medial thickening of arteries caused by smooth muscle cell accumulation and matrix deposition and extension of a muscular wall in intra-acinar vessels.7 The latter may result from increased proliferation of smooth muscle cells to more distal uncovered vessels or from recruitment and differentiation of pulmonary fibroblasts or pericytes to contractile smooth muscle cells. Another characteristic feature of vascular remodeling during pulmonary hypertension involves rarefaction of pulmonary arteries.8 Although poorly understood, rarefaction presumably reflects an adaptive structural response to prune insufficiently perfused "ghost" arterioles formed after severe microvascular constriction.9 As a consequence, pulmonary hypertension and right ventricular hypertrophy may develop, ultimately progressing to right heart failure. This constitutes a major cause of cardiopulmonary morbidity and mortality, for example, in patients with chronic obstructive lung disease, for which few medical treatments exist.
The precise molecular mechanisms that play a role in the pathogenesis of pulmonary hypertension and the structural changes in the pulmonary vasculature are only partly known.10 Pulmonary vasoconstriction appears to be of importance, and both endothelin and angiotensin have been implicated as important mediators.11 12 13 14 In contrast, the observation that mice deficient in endothelial nitric oxide synthase (eNOS) were found to develop excessive pulmonary hypertension,15 whereas adenoviral NOS gene transfer prevented hypoxia-induced pulmonary hypertension16 point to an important role of NO in the prevention of hypoxia-induced pulmonary vasoconstriction. In addition, several vascular cell mitogens such as heparin-binding epidermal growth factor,17 vascular endothelial cell growth factor,18 and platelet-derived growth factor19 appear to be implicated in the pathogenesis of pulmonary hypertension. Last, activation of proteases, in particular elastase, may be essential for extracellular matrix degradation associated with pulmonary vascular remodeling.20 Elastase was also shown to be able to induce the release of growth factors (such as basic fibroblast growth factor [b-FGF]) from the extracellular matrix, which may further contribute to pulmonary artery smooth muscle proliferation.21
Several observations point to an additional role of the plasminogen system in pulmonary hypertension. Similar to the role of elastase in extracellular matrix remodeling, there is evidence suggesting that enhanced plasmin proteolysis may contribute to pulmonary vascular remodeling. Indeed, hypoxia increases expression of u-PAR (the cellular receptor of urokinase-type plasminogen activator [u-PA], enhances plasma fibrinolytic activity, and upregulates expression of plasminogen (plg) activators during ventricular hypertrophy in response to hypoxia or overloading.22 23 24 Interestingly, and also similar to elastase, plasmin has been shown to induce the release of b-FGF from the extracellular matrix.25
To further investigate the role of the plasminogen system in the pathogenesis of pulmonary hypertension and right ventricular remodeling, mice with specific deficiencies in plasminogen, tissue-type plasminogen activator (t-PA), u-PA, or u-PAR were subjected to hypoxic conditions. The present findings implicate an important role of u-PA–mediated plasmin proteolysis in hypoxia-induced pulmonary vascular remodeling and subsequent right ventricular hypertrophy, which potentially might have important consequences for future therapeutic strategies in patients with (evolving) pulmonary hypertension.
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Methods |
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Animals and Experimental Protocol
The experiments were approved by the institutional review board and were conducted according to the guidelines for animal experiments of the National Institutes of Health. Transgenic mice and appropriate wild-type control mice were studied after being exposed to chronic hypoxia, as compared with normoxic conditions (controls). Experimental groups (n=11 to 14) consisted of the following adult (6 to 8 weeks old) mice: (1) t-PA-/- mice,26 (2) u-PA-/- mice,26 (3) u-PAR-/- mice,27 (4) plasminogen-/- mice,28 and (5) wild-type mice. In addition, newborn (p+7) u-PA-/-, t-PA-/-, and wild-type mice were studied. Mice were placed in a tightly sealed chamber under normobaric hypoxia (FIO2 10%). Genotypic identical normoxic control mice were maintained in identical conditions in room air (FIO2 21%).
Hemodynamic
Measurements
The right ventricular systolic
and diastolic pressures were measured in
anesthetized mice (sodium pentobarbital, 60 mg/kg IP) by
transthoracic
puncture.29 Right
ventricular pressure was measured continuously for 5
minutes with a pressure transducer (model AA 016, Baxter). Systemic
arterial blood pressure was continuously measured over a
5-minute period by insertion of the needle into the abdominal aorta.
Hemodynamic measurements were displayed on an
oscilloscope (Pressure Amplifier 863, Elema) and analyzed on a
PC-based computer program (Windaq Software version 1.37, Dataq
Instruments Inc).
Blood Sampling and Hematocrit
Measurement
Blood samples were collected from the abdominal aorta
and anticoagulated with EDTA (10 mmol/L). Hematocrit was measured
with an automated cell counter (Abbott Cell-Dyn 1330
system).
Measurement of Right Ventricular
Hypertrophy
The right ventricular free wall was
separated from the left ventricle and septum under a dissection
microscope.30 The right
ventricle and the left ventricle/septum were dried at 90° for 72
hours. Right ventricle and left ventricle plus septum were weighed
separately. Results are expressed as ratio of right ventricle weight
over left ventricle plus septum weight or right ventricle weight over
body weight.
Histology and Morphometric
Analysis
A cannula was introduced into the right atrium, and
mice were perfused with 1% phosphate-buffered
paraformaldehyde at 100 cm H2O
pressure for 5 minutes. Subsequently, the trachea was cannulated and
1% phosphate-buffered paraformaldehyde was perfused at
30 cm H2O through the airways. The heart and
lungs were removed en bloc, and the heart was separated from the lungs
and the large vessels. The samples were cryoembedded or postfixed for
24 hours in 1% phosphate-buffered paraformaldehyde,
dehydrated, and embedded in paraffin. Verhoeffs–van Gieson elastica
stains were performed on 4-µm sections. In addition, sections of the
heart (7 µm) were used for sirius red staining and
immunostaining of laminin, thrombomodulin, t-PA, u-PA,
or matrix metalloproteinase-9
(MMP-9).31 32 In
situ zymographic activity of t-PA and u-PA was performed with gel
overlays on 7-µm unfixed
cryosections.32
Hypoxia-induced pulmonary vascular remodeling was assessed by two different methods.34 First, the peripheral vessel density (defined as the number of vessels per 100 alveoli) was determined. Peripheral arteries were defined as all vessels landmarked to airway structures distal to the terminal bronchioli. Nonmuscularized and partly or fully muscularized vessels were scored separately. Second, media thickness was determined by measuring the diameter between the internal and external elastic lamina.
Right ventricular myocyte
hypertrophy was measured as the cross-sectional area of
50 individual cardiomyocytes per heart in the right
ventricle on laminin-stained sections to delineate the basement
membrane. The number of subendocardial capillaries was counted on
thrombomodulin-stained sections (to visualize
endothelial cells) and expressed as number of
capillaries per square millimeter. Collagen type I and III contents of
the right ventricle were quantified on sirius red–stained
sections.
Statistical Analysis
Results are presented as mean values ±SD.
Statistical analysis was performed by ANOVA and subsequent
Newman-Keuls test. A value of
P<0.05 was considered
statistically significant.
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Results |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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Hemodynamic Measurements
Adult wild-type mice that were exposed to 28 days of hypoxia showed a significant 1.8- to 2.7-fold rise in right ventricular pressure (Table 1
). The right ventricular
systolic and diastolic pressures were 37±3.8
mm Hg and 15±3.7 mm Hg, respectively, as compared with right
ventricular systolic and diastolic
pressures of 21±3.2 and 5.5±1.0 mm Hg in normoxic mice
(P<0.01). In
u-PA-/- mice, no such increase in right
ventricular pressure was seen. In contrast,
t-PA-/- mice showed a rise in right
ventricular pressure in response to hypoxia that
was fully comparable with that of wild-type mice. Mice with a
deficiency in the u-PA receptor showed a partial but significant
hypoxia-induced enhancement in right ventricular
pressure. Plasminogen-deficient mice had no significant
increase in right ventricular pressure in response to
hypoxia. Hypoxia did not affect mean
arterial blood pressure in any of the groups
(Table 1). Hypoxia resulted in an increase in an
identical hematocrit from 48.7±1.0% to
61.1±0.9%.
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Right Ventricular Weight
In wild-type mice, hypoxia caused a 1.7-fold
increase in the right ventricle/left ventricle+septum ratio and a
1.8-fold increase in the right ventricle weight/body weight ratio
(Figure 1). In accordance with the right
ventricular pressure measurements,
u-PA-/- and
plg-/- mice did not show any increase in
right ventricular weight, whereas t-PA–deficient mice
showed right ventricular hypertrophy that was
comparable to wild-type mice. Hypoxia caused a significant
increase in right ventricular weight in
u-PAR-/- mice; however, again this
increase was more modest as compared with the increase in wild-type
mice (RV/LV+S ratio in u-PAR-/- mice
42±6% as compared with 51±5% in wild-type mice,
P<0.05).
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In newborn mice (10 days hypoxia), a similar pattern
was observed
(Figure 2). Both the right ventricle/left ventricle+septum
ratio and the right ventricle weight/body weight ratio were markedly
increased in wild-type mice (1.7- to 1.9-fold) and
t-PA-/- mice (1.6- to 2.0-fold) exposed
to hypoxia. In contrast, u-PA-/-
mice did not show any significant increase in right
ventricular hypertrophy in response to
hypoxia. Total body weight was not different between hypoxic
and normoxic mice of all different
genotypes.
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Pulmonary Vascular Remodeling
Hypoxia induced mild vascular rarefaction in
the lungs of wild-type mice
(Table 2). In wild-type mice exposed to hypoxia, a
29% reduction in nonmuscularized vessels and a 22% reduction in
partly or fully muscularized arterioles were observed
(P<0.05). Both
u-PA-/- mice and
plg-/- mice did not show such a
reduction in vascular density in response to hypoxia. The
hypoxia-induced rarefaction in
t-PA-/- mice was similar to that in
wild-type mice. U-PAR-/- mice showed an
intermediate reduction in the number of arteries per 100
alveoli.
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The increase in smooth muscle cells within the distal
arterial walls, as reflected by the increase in media
thickness, followed a similar pattern. In wild-type mice,
hypoxia caused an 
2-fold increase in the ratio of media
thickness over vascular diameter, which was similar in
t-PA-/- mice. Conversely,
u-PA-/- mice and
plg-/- mice did not show an increase in
media thickness
(Table 2
and
Figure 3). In mice with a deficiency of the u-PA receptor, a
significant increase in media thickness was observed, however, to a
lesser extent than the increase seen in wild type or
t-PA-/- mice. Interestingly, hypoxic
wild-type or t-PA-/- mice showed a
marked fragmentation of the elastic membrane, whereas this was not seen
in u-PA-/- or
plg-/- mice
(Figure 3).
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Pulmonary vascular remodeling in response to hypoxia was somewhat more pronounced in newborn wild-type mice (data not shown) but was again completely absent in u-PA-/- mice.
There were no differences in pulmonary vascular density or media thickness between genotypes at normoxic conditions.
Histological Analysis
of Right Ventricular Hypertrophy
Histological analysis revealed
a hypoxia-induced increase in right ventricular
cardiomyocyte size from 250±40
µm2 to 340±68
µm2 in wild-type mice, which was not
present in u-PA-/- mice
(Table 3). Also, the almost 2-fold increase in collagen
content of the right ventricular wall in hypoxic wild-type
mice was not seen in u-PA-/- mice
(Figure 4 and
Table 3). Right ventricular remodeling on
hypoxia in wild-type mice was associated with a small but
nonsignificant reduction in subendocardial capillary density (from
5200±210 per mm2 to 4400±260 per
mm2).
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Expression and Zymographic Activity of
Plasminogen Activators and MMP-9 in Lung
and Heart
Immunostaining for u-PA revealed
enhanced u-PA expression in lungs of hypoxic wild-type mice, in
particular located near vascular smooth muscle cells
(Figure 5). Zymographic analysis showed a
1.8±0.3-fold increase in u-PA activity in these lungs. In addition,
there was increased MMP-9 expression (which might be seen as a
candidate for u-PA–mediated plasmin
formation)30 related to
macrophages, in particular around the pulmonary
vasculature. There was no major difference in the expression or
zymographic activity of plasminogen activators
in hearts from hypoxic mice as compared with hearts from normoxic
controls.
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Discussion |
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In this study, the role of the plasminogen/plasmin system in the pathogenesis of hypoxia-induced pulmonary hypertension and right ventricular hypertrophy was investigated. Chronic exposure to hypoxia resulted in increased pulmonary hypertension and right ventricular hypertrophy,29 associated with a marked remodeling of the pulmonary vasculature, characterized by a vascular rarefaction and an increase in media thickness of peripheral pulmonary arteries. However, u-PA-/- and plg-/- mice were resistant to these hypoxia-induced anatomical and functional changes, whereas t-PA-/- mice responded to hypoxia in an identical manner as wild-type mice. Hypoxic u-PAR-/- mice showed an intermediate response, which is significantly lower than wild-type mice. Hence, the plasminogen system is involved in hypoxia-induced pulmonary vascular remodeling and associated functional changes. In particular, u-PA appears to be of essential importance for the development of hypoxia-induced pulmonary hypertension. Because both u-PA-/- and plg-/- mice showed a similar lack of response to hypoxia, it may be assumed that u-PA acts by conversion of plasminogen to plasmin. The role of u-PA was further substantiated by the demonstration of upregulated u-PA expression and activity in hypoxic lungs. Ample evidence indicates that u-PA–mediated plasmin generation may play a pivotal role in tissue remodeling.31 32 33 It has been demonstrated in vivo that u-PA is essential for arterial neointima formation and adequate wound healing on vascular injury and for left ventricular remodeling after myocardial infarction.32 33 In contrast, t-PA, which is the major activator of plasma fibrinolytic activity, did not play an important role in the vascular remodeling and associated changes, which is in line with previous observations in other models.32 33 It should be noted that our observations do not exclude that the hypoxia-induced effects are related to a mediator other than hypoxia per se. For example, an increase in cardiac output and changes in hematocrit or vasoconstriction may contribute to the signaling that induced increased u-PA expression.
Although the exact mechanism of the hypoxia-induced changes in the pulmonary vasculature remains to be established, it can be assumed that it at least partly depends on the ability of cells to proliferate across anatomic borders, such as the elastic laminae. The present observation that u-PA-/- and plg-/- mice did not show hypoxia-induced fragmentation of the elastic membrane may explain the absence of pulmonary vascular remodeling in u-PA–deficient or plg-deficient mice. It is, however, not completely clear which mechanism can be held responsible for the hypoxia-induced rarefaction of pulmonary vessels, which was also less prominent in u-PA-/- and plg-/- mice.
Interestingly, hypoxia-induced pulmonary vascular remodeling was partly reduced in u-PAR–deficient mice as well. This observation indicates that the u-PA–induced effects in response to hypoxia are in part mediated by the u-PA receptor. Because u-PAR is expressed on smooth muscle cells and it has been shown that binding of u-PA to u-PAR may significantly affect smooth muscle cell adhesion to matrix proteins,34 u-PAR may play an additional supportive though not essential role in the u-PA–mediated response on hypoxia.
Our findings might have some relevance for the management of hypoxic pulmonary hypertension and right ventricular hypertrophy in patients because the murine hypoxia model has generally been accepted as a model for human hypoxic disease.8 35 Hypothetically, selective inhibition of u-PA activity or interference in the u-PA binding to the u-PA receptor (although to a lesser extent) might be of benefit for patients with pulmonary vascular disease caused by chronic hypoxia. At present, there is no specific therapy for this condition, and the occurrence of pulmonary vascular disease and secondary right ventricular hypertrophy and subsequent right heart failure is associated with considerable morbidity and mortality. However, further study in other models and in patients with hypoxic pulmonary hypertension is warranted before definitive conclusions regarding a potential therapeutic relevance of the present observations can be made.
Conclusions
Loss of the u-PA or plasminogen gene
protects against the development of hypoxia-induced
pulmonary hypertension, pulmonary vascular remodeling,
and right ventricular hypertrophy. These
observations indicate an essential role of the plasminogen
system as a mediator of the direct or indirect adaptive responses to
chronic hypoxia and in the occurrence of hypoxic
pulmonary vascular
disease.
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Acknowledgments |
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Marcel Levi is an investigator of the Royal Dutch Academy of Arts and Sciences. The skillful technical support of Ann Manderveld, Kathleen Maris, and Maria De Mol and the assistance with artwork by Ann Vandenhoeck are gratefully acknowledged.
Received August 10, 2000; revision received November 6, 2000; accepted November 6, 2000.
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References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionReferences |
|---|
1. Dor Y, Keshet E. Ischemia-driven angiogenesis. Trends Cardiovasc Med. 1997;7:289–294.
2. Pfeifer M, Blumberg FC, Wolf K, et al. Vascular remodeling and growth factor gene expression in the rat lung during hypoxia. Respir Physiol. 1998;111:201–212.[Medline] [Order article via Infotrieve]
3.
Li H, Elton TS,
Chen YF, et al. Increased endothelin receptor gene expression in
hypoxic rat lung. Am J
Physiol. 1994;266:L553–L560.
4. Kourembanas S, Marsden PA, McQuillan LP, et al. Hypoxia induces endothelin gene expression and secretion in cultured human endothelium. J Clin Invest. 1991;88:1054–1057.
5. Riva C, Chauvin C, Pison C, et al. Cellular physiology and molecular events in hypoxia-induced apoptosis. Anticancer Res. 1998;18:4729–4736.[Medline] [Order article via Infotrieve]
6.
Carmeliet P, Dor Y,
Herbert JM, et al. Role of HIF-1
in hypoxia-mediated
apoptosis, cell proliferation, and tumor angiogenesis.
Nature. 1998;394:485–490.[Medline]
[Order article via Infotrieve]
7.
Thompson BT,
Steigman DM, Spence CL, et al. Chronic hypoxic pulmonary
hypertension in the guinea pig: effect of three levels of
hypoxia. J Appl
Physiol. 1993;74:916–921.
8. Jones R, Reid L. Vascular Remodeling in Clinical and Experimental Pulmonary Hypertension. London, UK: Portland Press Ltd; 1995:47–116.
9. le Noble FA, Stassen FR, Hacking WJ, et al. Angiogenesis and hypertension. J Hypertens. 1998;16:1563–1572.[Medline] [Order article via Infotrieve]
10.
Rabinovitch
M. Pulmonary hypertension: updating a mysterious disease.
Cardiovasc Res. 1997;34:268–272.
11.
Huabin LI, Chen
S-J, Chen Y-F, et al. Enhanced endothelin-1 and endothelin receptor
gene expression in chronic hypoxia.
J Appl Physiol. 1994;77:1451–1459.
12. Morell NW, Atochina EN, Morris KG, et al. Angiotensin converting enzyme expression is increased in small pulmonary arteries of rats with hypoxia-induced pulmonary hypertension. J Clin Invest. 1995;96:1823–1833.
13. Chen S-J, Chen Y-F, Opgenort TJ, et al. The orally active nonpeptide endothelin A-receptor antagonist A-127722 prevents and reverses hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling in Sprague-Dawley rats. J Cardiovasc Pharmacol. 1997;29:713–725.[Medline] [Order article via Infotrieve]
14. Herget J, Pelouch V, Kolar F, et al. The inhibition of angiotensin converting enzyme attenuates the effect of chronic hypoxia on pulmonary blood vessels in the rat. Physiol Res. 1996;45:221–226.[Medline] [Order article via Infotrieve]
15. Fagan KA, Fouty BW, Tyler RC, et al. The pulmonary circulation of homozygous and heterozygous eNOS-null mice is hyperresponsive to mild hypoxia. J Clin Invest. 1999;103:291–299.[Medline] [Order article via Infotrieve]
16. Janssens SP, Bloch KD, Nong Z, et al. Adenoviral-mediated transfer of the human endothelial nitric oxide synthase gene reduces acute hypoxic pulmonary vasoconstriction in rats. J Clin Invest. 1996;98:317–324.[Medline] [Order article via Infotrieve]
17. Powell PP, Klagsbrun M, Abraham JA, et al. Eosinophils expressing heparin-binding EGF-like growth factor mRNA localize around lung microvessels in pulmonary hypertension. Am J Pathol. 1993;143:784–793.[Abstract]
18.
Christou H,
Yoshida A, Arthur V, et al. Increased vascular
endothelial growth factor production in the
lungs of rats with hypoxia-induced pulmonary
hypertension. Am J Respir Cell Mol
Biol. 1998;18:768–776.
19. Kourembanas S, Hannan RL, Faller DV. Oxygen tension regulates the expression of platelet-derived growth factor-B chain in human endothelial cells. J Clin Invest. 1990;86:670–674.
20.
Maruyama K, Ye C,
Woo M, et al. Chronic hypoxic pulmonary hypertension in rats
and increased elastolytic activity.
Am J Physiol. 1991;261:H1716–H1726.
21. Thompson K, Rabinovitch M. Exogenous leucocyte and endogenous elastases can mediate mitogenic activity in pulmonary artery smooth muscle cells by release of extracellular matrix-bound basic fibroblast growth factor. J Cell Physiol. 1996;166:495–505.[Medline] [Order article via Infotrieve]
22. Pinsky DJ, Liao H, Lawson CA, et al. Hypoxia-mediated suppression of fibrinolysis enhances pulmonary vascular fibrin deposition. J Clin Invest. 1998;102:919–928.[Medline] [Order article via Infotrieve]
23.
Graham CH,
Fitzpatrick TE, McCrae KR. Hypoxia stimulates urokinase
receptor expression through a heme protein-dependent pathway.
Blood. 1998;91:3300–3307.
24. Bansal DD, Klein RM, Hausmann EH, et al. Secretion of cardiac plasminogen activator during hypoxia-induced right ventricular hypertrophy. J Mol Cell Cardiol. 1997;29:3105–3114.[Medline] [Order article via Infotrieve]
25.
Saksela O, Rifkin
DB. Release of basic fibroblast growth factor-heparan sulfate complexes
from endothelial cells by plasminogen
activator-mediated proteolytic activity.
J Cell Biol. 1990;110:767–775.
26. Carmeliet P, Schoonjans L, Kieckens L, et al. Physiological consequences of loss of plasminogen activator gene function in mice. Nature. 1994;368:419–424.[Medline] [Order article via Infotrieve]
27. Dewerchin M, van Nuffelen A, Wallays G, et al. Generation and characterization of urokinase receptor-deficient mice. J Clin Invest. 1996;97:870–878.[Medline] [Order article via Infotrieve]
28.
Ploplis VA,
Carmeliet P, Vazirzadeh S, et al. Effects of disruption of the
plasminogen gene on thrombosis, growth, and health in mice.
Circulation. 1995;92:2585–2593.
29. Hales CA, Kradin RL, Brandstetter RD, et al. Impairment of hypoxic pulmonary artery remodeling by heparin in mice. Am Rev Respir Dis. 1983;128:747–751.[Medline] [Order article via Infotrieve]
30. Fulton RM, Hutchinson EC, Jones M. Ventricular weight in cardiac hypertrophy. Br Heart J. 1952;14:413–420.
31. Carmeliet P, Moons L, Lijnen R, et al. Urokinase-generated plasmin activates matrix metalloproteinases during aneurysm formation. Nat Genet. 1997;17:439–444.[Medline] [Order article via Infotrieve]
32.
Carmeliet P,
Moons L, Herbert JM, et al. Urokinase-type but not tissue-type
plasminogen activator mediates
arterial neointima formation in mice.
Circ Res. 1997;81:829–839.
33. Heymans S, Luttun A, Nuyens D, et al. Inhibition of plasminogen activators or matrix metalloproteinases prevents cardiac rupture but impairs therapeutic angiogenesis and causes cardiac failure. Nat Med. 1999;5:1135–1142.[Medline] [Order article via Infotrieve]
34.
Chang AW, Kuo A,
Barnathan ES, et al. Urokinase-dependent upregulation of smooth muscle
cell adhesion to vitronectin by urokinase.
Arterioscler Thromb Vasc Biol. 1998;18:1855–1860.
35. Hunter C, Barer GR, Shaw JW, et al. Growth of the heart and lungs in the hypoxic rodents: a model for human hypoxic disease. Clin Sci. 1974;46:375–391.
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 S. L. Merklinger, R. A. Wagner, E. Spiekerkoetter, A. Hinek, R. H. Knutsen, M. G. Kabir, K. Desai, S. Hacker, L. Wang, G. M. Cann, et al. Increased Fibulin-5 and Elastin in S100A4/Mts1 Mice With Pulmonary Hypertension Circ. Res., September 16, 2005; 97(6): 596 - 604. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Otto, L. Hein, M. Brede, R. Jahns, S. Engelhardt, H.-J. Grone, and G. Schutz Pulmonary Hypertension and Right Heart Failure in Pituitary Adenylate Cyclase-Activating Polypeptide Type I Receptor-Deficient Mice Circulation, November 16, 2004; 110(20): 3245 - 3251. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Nishiuma, T. H. Sisson, N. Subbotina, and R. H. Simon Localization of Plasminogen Activator Activity within Normal and Injured Lungs by In Situ Zymography Am. J. Respir. Cell Mol. Biol., November 1, 2004; 31(5): 552 - 558. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. M. Razzaq, R. Bass, D. J. Vines, F. Werner, S. A. Whawell, and V. Ellis Functional Regulation of Tissue Plasminogen Activator on the Surface of Vascular Smooth Muscle Cells by the Type-II Transmembrane Protein p63 (CKAP4) J. Biol. Chem., October 24, 2003; 278(43): 42679 - 42685. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. M. Hale, M. J. Shoichet, T. L. Bushfield, and M. A. Adams Time Course of Vascular Structural Changes During and After Short-Term Antihypertensive Treatment Hypertension, August 1, 2003; 42(2): 171 - 176. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Dai, H. Guan, L. Liu, S. Little, G. McFadden, S. Vaziri, H. Cao, I. A. Ivanova, L. Bocksch, and A. Lucas Serp-1, a Viral Anti-inflammatory Serpin, Regulates Cellular Serine Proteinase and Serpin Responses to Vascular Injury J. Biol. Chem., May 9, 2003; 278(20): 18563 - 18572. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Eddahibi, N. Morrell, M-P. d'Ortho, R. Naeije, and S. Adnot Pathobiology of pulmonary arterial hypertension Eur. Respir. J., December 1, 2002; 20(6): 1559 - 1572. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Nassar, A. Haj-Yehia, S.'e. Akkawi, A. Kuo, K. Bdeir, A. Mazar, D. B. Cines, and A. A.-R. Higazi Binding of Urokinase to Low Density Lipoprotein-related Receptor (LRP) Regulates Vascular Smooth Muscle Cell Contraction J. Biol. Chem., October 18, 2002; 277(43): 40499 - 40504. [Abstract] [Full Text] [PDF]
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