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Published ahead of print on September 4, 2003, doi:10.1164/rccm.200302-282OC
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American Journal of Respiratory and Critical Care Medicine Vol 169. pp. 39-45, (2004)
© 2004 American Thoracic Society

Chronic Sildenafil Treatment Inhibits Monocrotaline-induced Pulmonary Hypertension in Rats

Ralph T. Schermuly, Klaus P. Kreisselmeier, Hossein A. Ghofrani, Hüseyin Yilmaz, Ghazwan Butrous, Leander Ermert, Monika Ermert, Norbert Weissmann, Frank Rose, Andreas Guenther, Dieter Walmrath, Werner Seeger and Friedrich Grimminger

Departments of Internal Medicine and Pathology, Justus-Liebig-University Giessen, Giessen, Germany; and Pfizer Global Research and Development, Sandwich, United Kingdom

Correspondence and requests for reprints should be addressed to Ralph Schermuly, Ph.D., Zentrum für Innere Medizin, Justus-Liebig-Universität Giessen, Klinikstrasse 36, 35392 Giessen, Germany. E-mail: ralph.schermuly{at}innere.med.uni-giessen.de


   ABSTRACT
TOP
 ABSTRACT
METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Sildenafil, a phosphodiesterase 5 inhibitor, is currently under investigation for therapy of pulmonary hypertension. This study was designed to investigate chronic effects of sildenafil in monocrotaline (MCT)-induced pulmonary hypertension in rats. Four weeks after a single subcutaneous injection of MCT, the animals displayed nearly threefold elevated pulmonary artery pressure and vascular resistance values, with a concomitant decline in central venous oxygen saturation and arterial oxygenation. Marked right heart hypertrophy was evident, and massive thickening of the precapillary artery smooth muscle layer was histologically apparent. Further deterioration of pulmonary hypertension occurred 6 weeks after MCT injection, with some animals dying during this period because of right heart failure. When chronically administered from Days 14–28, sildenafil significantly increased plasma cyclic guanosine monophosphate and inhibited the development of pulmonary hypertension and right heart hypertrophy, with preservation of gas exchange and systemic arterial pressure. A corresponding efficacy profile was also noted for long-term feeding with sildenafil from Days 28–42. Moreover, the death rate significantly decreased in those animals treated with sildenafil. We conclude that sildenafil attenuates MCT-induced pulmonary hypertension and cor pulmonale in rats.

Key Words: pulmonary hypertension • monocrotaline • phosphodiesterase inhibitor • phosphodiesterase • sildenafil

Pulmonary arterial hypertension is a fatal disease, often affecting young people (1, 2). It is characterized by intimal lesions, medial hypertrophy, and adventitial thickening of precapillary pulmonary arteries. Because of the severe increase in afterload, right ventricular hypertrophy and right heart failure develop. Increased vasomotor tone and chronic remodeling of the precapillary resistance vessels, including marked vascular smooth muscle cell growth, are assumed to be underlying pathogenetic mechanisms.

Recent short-term studies in patients suffering from pulmonary hypertension suggest that the phosphodiesterase (PDE) 5 inhibitor sildenafil is an effective pulmonary vasodilator (3–10). This agent has been approved for erectile dysfunction, possesses excellent availability after oral intake, and has undergone extensive toxicologic testing (11, 12). PDEs hydrolyze second messengers of the pulmonary vasodilator agents prostacyclin and nitric oxide, namely cAMP and cyclic guanosine monophosphate (cGMP) (13). Recent studies showed that the cGMP-specific PDE5 is highly expressed in lung tissue (14, 15). Moreover, further upregulation of PDE5 may occur under conditions of pulmonary hypertension, thereby contributing to increased lung vascular resistance under these conditions (16–18).

Beyond acute pulmonary vasodilation, PDE inhibitors may also possess antiremodeling potency via increased cAMP and cGMP levels (19), thus offering the possibility of beneficial long-term administration. In this study, we addressed this issue in a model of chronic pulmonary hypertension, employing the alkaloid monocrotaline (MCT). This toxin from plants of the Crotalaria species (20) causes pulmonary arterial endothelial cell injury and subsequent pulmonary artery smooth muscle hypertrophy with persistent severe pulmonary hypertension after one injection in rats (21). We investigated the chronic efficacy of oral sildenafil in this model and particularly addressed the question of whether long-term daily intake of sildenafil (1) during development of pulmonary hypertension and (2) after full establishment of MCT-induced pulmonary hypertension might exert beneficial effects on lung vascular remodeling, right heart hypertrophy, and survival. Some of the results of these studies have been previously reported in the form of an abstract (22).


   METHODS
TOP
 ABSTRACT
 METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
MCT Treatment
MCT (Sigma, Deishofen, Germany) was dissolved in 0.5 N of HCl, and the pH was adjusted to 7.4 with 0.5 N of NaOH. The solution was given as a single subcutaneous injection (60 mg/kg) to male Sprague Dawley rats. Control rats received an equal volume of isotonic saline.

Surgical Preparation and Tissue Preparation
The animals were initially anesthetized with intraperitoneal pentobarbital and were ventilated with 10 ml/kg body weight and a frequency of 60 s-1 (SAR830A/P; IITC, Woodland Hills, CA) after tracheostomy. The FIO2 was set at 0.5, and a positive end-expiratory pressure of 1.5 cm H2O was used throughout. Anesthesia was maintained by inhalation of isoflurane.

Hemodynamic Measurements
A right heart catheter (PE 50 tubing) was inserted through the right jugular vein for measurement of right ventricular pressure, and the left arteria carotis was cannulated for arterial pressure monitoring. Cardiac output was measured by thermodilution technique (Cardiotherm 500-X; Hugo-Sachs Electronic–Harvard Apparatus GmbH, March-Hugstetten, Germany). Briefly, a thermistor catheter (1.5°F) was forwarded into the ascending thoracic aorta via the right carotid artery for the measurement of transpulmonary thermodilution cardiac output. A 0.15-ml bolus of room-temperature saline was injected into the right ventricle as an indicator, and cardiac output was averaged from three consecutive determinations and indexed to the weight of the animal to obtain the cardiac index. After exsanguinations, the left lung was fixed for histology in 10% neutral-buffered formalin, and the right lung was frozen in nitrogen.

Measurement of Organ Weight
The heart was dissected, and the ratio of the right ventricle to left ventricle plus septum weight (RV/LV + S) was calculated as an index of right ventricular hypertrophy.

Measurement of Plasma cGMP Level
cGMP levels were determined using a radioimmunoassay (Immunotech, Marseille, France), as described (23). The cGMP concentrations in plasma were expressed as pmol per ml.

Western Blot Assay
Frozen lung tissues were homogenized and centrifuged at 13,000 rpm for 30 minutes. The supernatants were measured for protein content using Dye Reagent Concentrate (Bio-Rad, Munich, Germany). Extracts containing equal amounts of protein (10 µg for matrix metalloproteinase [MMP-2] and 30 µg for MMP-9) were denatured and separated on 7.5% sodium dodecyl sulfate polyacrylamide gels. The separated proteins were blotted on a polyvinylidene fluoride membrane with a semidry transfer unit at 100 mA for 2 hours. The blots were blocked and developed with 0.3 and 0.2 µg/ml of rabbit polyclonal IgG antibodies for specific rat MMP-2 and MMP-9 and a 1/7,500 dilution of horseradish peroxidase–labeled goat anti-rabbit IgG (Abcam Ltd., Cambridge, UK). The bands were visualized using an enhanced chemiluminescence detection system (Amersham Corp., Arlington Heights) and quantified by densitometry.

Paraffin Embedding and Microscopy
Fixation was performed by immersion of the lungs in a 3% paraformaldehyde solution. For paraffin embedding, whole lung was dissected in tissue blocks from all lobes. Sectioning at 10 µm was performed from all paraffin-embedded blocks. Hematoxylin and eosin elastica staining was performed according to common histopathologic procedures. Light microscopic slides were analyzed in a blind fashion without the knowledge of treatment groups. In each rat, 40 to 50 intraacinar arteries were categorized as muscular (i.e., with a complete medial coat of muscle), partially muscular (i.e., with only a crescent of muscle), or nonmuscular (i.e., no apparent muscle), as reported (24). Microscopy and photography were performed with a Nikon UFX-II microscope with a Nikon D1 attached to the phototube at a magnification of x100–x400.

Experimental Protocols
For chronic studies, rats were randomized to receive either placebo of sildenafil in the drinking water. Six groups were studied: control28, control animals for 28 days (n = 8); control42, control animals for 42 days (n = 8); MCT28, MCT-treated animals for 28 days (n = 20); MCT42, MCT-treated animals for 42 days (n = 25); MCT28/Sil14–28, 100 µg/kg per day of sildenafil from Day 14 to Day 28 (n = 15); MCT42/Sil28–42, 100 µg/kg per day of sildenafil from Day 28 to Day 42 (n = 20).

Data Analysis
All data are given as means ± SEM. Differences between groups were assessed by the use of analysis of variance and the Student-Newman-Keuls post hoc test for multiple comparisons, with a p value of less than 0.05 regarded to be significant. The survival rate was presented as Kaplan-Meier curve and compared by log-rank test; p values of less than 0.05 were considered significant.


   RESULTS
TOP
 ABSTRACT
 METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
MCT-treated (28 days [n = 10], 42 days [n = 10]) Rats (MCT28, MCT42)
MCT-treated rats had significantly increased right ventricular systolic pressure values on Day 28 (59.8 ± 3.6 mm Hg), with a further increase on Day 42 (71.1 ± 6.0 mm Hg), as compared with saline-injected control animals (25.7 ± 2.0 mm Hg) (Figure 1 ; Table 1) . This was also true for right ventricular hypertrophy: The RV/LV + S ratio increased from 0.29 ± 0.01 to 0.51 ± 0.03 (28 days) and 0.76 ± 0.04 (42 days) (p < 0.05), respectively (Figure 2) . Cardiac index was reduced (although not significantly) on Day 28 (29.5 ± 2.8 ml/min 100 g body weight) and Day 42 (30.8 ± 3.2 ml/min 100 g body weight), with control subjects ranging 34.6 ± 3.1 ml/min 100 g body weight. No significant changes in systemic arterial pressure occurred. The pulmonary vascular resistance index was increased on Day 28 (2.20 ± 0.19 mm Hg min/ml 100 g body weight) and Day 42 (2.44 ± 0.15 mm Hg min/ml 100 g body weight ) (control subjects 0.91 ± 0.05 mm Hg min/ml 100 g body weight), whereas systemic vascular resistance did not change significantly. Both MCT-treated groups had significantly lower values of arterial Po2-13-13-13-13-13-13-13-13-13-13-13–13–13> and central venous oxygen saturation (Figure 3) . Moreover, the body weight was lower than that of the time-matched control animals. All rats of the control groups survived for the entire experimental period (n = 8 each). The survival rate of the MCT28 group decreased gradually to 70% at Day 28 (14 of 20) and in the MCT42 group to 48% at Day 42 (12 of 25) (Figure 4) . As compared with normal pulmonary arteries, a single injection of MCT resulted in severe media hypertrophy after 42 days (Figure 5) . Treatment with MCT was associated with a significant increase in distal pulmonary artery muscularization (Figure 6) on Day 28 with further progression on Day 42. As compared with control animals, an increase in plasma cGMP levels from 7.7 ± 1.4 to 13.8 ± 2.1 pmol/ml at Day 28 (p = NS) and 16.5 ± 1.6 pmol/ml at Day 42 (p < 0.05), respectively, was noted. Increased protein expression of gelatinases MMP-2 and MMP-9 in lung homogenate was detected (Figures 7A and 7B) .



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  		Figure 1. Influence of oral sildenafil from Day 14 to Day 28 (left) and Day 28 to Day 42 (right) on monocrotaline (MCT)-induced pulmonary hypertension. Right ventricular systolic pressure (RVPsys), systemic arterial pressure (SAP), and cardiac index (CI) are given (mean ± SEM). Animals were treated from Day 14 to Day 28 (left) or from Day 28 to Day 42 (right) with 100 µg/kg per day of sildenafil. *p < 0.05 as compared with control subjects; {dagger}p < 0.05 as compared with MCT28 or MCT42.

 

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  		TABLE 1. Summarized data of hemodynamics and blood gases in rats with monocrotaline-induced pulmonary hypertension and treatment with sildenafil

 


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  		Figure 2. Influence of oral sildenafil from Day 14 to Day 28 (left) and Day 28 to Day 42 (right) on MCT-induced pulmonary hypertension. Pulmonary vascular resistance index (PVRI), systemic vascular resistance index (SVRI), and right to left ventricular weight ratio (RV/LV + S) are given (mean ± SEM). Animals were treated from Day 14 to Day 28 (left) or from Day 28 to Day 42 (right) with 100 µg/kg per day of sildenafil. *p < 0.05 as compared with control subjects; {dagger}p < 0.05 as compared with MCT28 or MCT42.

 


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  		Figure 3. Influence of oral sildenafil from Day 14 to Day 28 (left) and Day 28 to Day 42 (right) on body weight and blood gases in MCT-induced pulmonary hypertension. Body weight, arterial oxygenation (PaO2/FIO2), and mixed venous oxygen saturation (SvO2) are given (mean ± SEM). Animals were treated from Day 14 to Day 28 or from Day 28 to Day 42. *p < 0.05 versus the corresponding control group; {dagger}p < 0.05 versus the corresponding MCT (MCT28 or MCT42) group.

 


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  		Figure 4. Survival rates of the different experimental groups. For exploration of the groups, see Figure 1 (*p < 0.05 for MCT42/Sil28–42 vs. MCT42). p.o. = oral application.

 


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  		Figure 5. Sildenafil suppresses pulmonary artery media hypertrophy. Hematoxylin and eosin elastica staining of paraffin embedded rat lung tissue. (A) Control lung: Bronchiolus with concomitant peribronchial artery. (Inlay) Small intrapulmonary artery. (B) Peribronchial arteries of rats 42 days after monocrotaline treatment: markedly thickened arterial walls with hypertrophic media and endothelial lesions. (Inlay) Extensive media hypertrophy in small arteries within the lung parenchyma. (C) Sildenafil treatment of MCT-exposed animals (MCT42/Sil28–42) reduces arterial wall thickening in peribronchial arteries, as well as in small intrapulmonary arteries (inlay).

 


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  		Figure 6. Effect of sildenafil on the degree of muscularization of peripheral pulmonary arteries. Percentage of nonmuscularized (nm), partially muscularized (pm), or fully (m) muscularized pulmonary arteries related to the total number of pulmonary arteries. A total of 40 to 50 intra-acinar vessels were analyzed in each lung from rats exposed to MCT for 28 or 42 days and sildenafil-treated groups (treatment from Days 14 to 28 or from Days 28 to 42). Fully muscularized arteries are compared by statistical analysis. *p < 0.05 versus control; {dagger}p < 0.05 versus MCT28; {ddagger}p <0.05 versus MCT42.

 


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  		Figure 7. Autoradiograms of immunoblots of matrix metalloproteinase (MMP)-2 and MMP-9. Homogenates of lung tissue were examined from sildenafil-treated animals. (A) Representative Western blots for MMP-2 in the early and late treatment group. (B) The Western blots of MMP-9 in the early and late treatment group. Immunoblots are representative of n = 4 blots for each group, showing identical results.

 
Long-term Oral Sildenafil in MCT-treated Rats (MCT28/Sil14–28 [n = 8], MCT42/Sil28–42 [n = 8])
When compared with MCT28, sildenafil-treated animals had significant lower values of right ventricular pressure (46.2 ± 5.6 mm Hg) and pulmonary vascular resistance index (1.59 ± 0.23 mm Hg min/ml 100 g body weight) (Figure 1) at the end of the experiments. This was also true for the RV/LV + S ratio, which decreased in response to the treatment (0.42 ± 0.03) (Figure 2). No change in cardiac index was noted, and systemic arterial pressure and the systemic vascular resistance index did not change significantly in the treatment group. Arterial oxygenation and central venous oxygen saturation increased in response to the sildenafil treatment (Figure 3). The death rate corresponded to that in the MCT28 group (Figure 4). Protein content of MMP-2 and MMP-9 decreased in the treatment group (Figure 7).

Treatment from Days 28 to 42 (MCT42/Sil28–42) resulted in a lower right ventricular systolic pressure (56.0 ± 2.2 mm Hg vs. 71.1 ± 6.0 mm Hg [MCT42]) and pulmonary vascular resistance index (1.99 ± 0.25 vs. 2.44 ± 0.15 mm Hg min/ml 100 g body weight, p < 0.05). Concomitantly, the RV/LV + S ratio decreased from 0.76 ± 0.04 to 0.61 ± 0.03. No significant changes in cardiac index and systemic vascular resistance index were noted. The PO2/FIO2 and mixed venous oxygen saturation values surpassed those in the MCT-treated control subjects (Figure 3). Fewer animals died in the MCT42/Sil28–42 group as compared with the MCT42 group (70% [14 of 20] vs. 48% [12 of 25]) (Figure 4). As shown in Figure 5, media hypertrophy was reduced in sildenafil-treated rats. Quantitative morphometric analysis demonstrated a significant reduction of fully muscularized distal pulmonary arteries in both treatment groups (Figure 6). As compared with MCT-treated animals, a significant increase in plasma cGMP levels occurred under sildenafil treatment: from 13.8 ± 2.1 to 34.7 ± 3.1 pmol/ml at Day 28 (p < 0.05) and from 16.5 ± 1.6 to 42.6 ± 2.9 pmol/ml at Day 42 (p < 0.05). This was accompanied by a decrease in MMP-2 and MMP-9 protein content for both enzymes (Figure 7).


   DISCUSSION
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
The pyrrolizidine alkaloid MCT is used experimentally to cause pulmonary hypertension in rats. The proposed mechanism of action includes activation of MCT by the liver to the putative electrophile MCT pyrrole (20, 21, 25), which causes endothelial injury in the pulmonary vasculature with subsequent remodeling of the precapillary vessels (medial thickening, de novo muscularization of small pulmonary arterioles). Because of this mimicry of clinical pulmonary arterial hypertension, the rat MCT model has repeatedly been employed for investigating acute hemodynamic and gas exchange effects of vasodilators and chronic antiremodeling effects of antiinflammatory and antiproliferative agents (26–29). Reproducible induction of severe, progressive pulmonary hypertension in response to MCT was also achieved in this study.

Both pulmonary vascular resistance and pulmonary artery pressure increased approximately threefold, accompanied by a significant decrease in arterial and venous oxygenation and some (nonsignificant) reduction of cardiac index. In line with these findings, an impressive right heart hypertrophy, obvious from the weight ratio of right to left ventricle plus septum, was observed. This was accompanied by a weight loss of the animals because of the severity of the disease. Some animals died most probably because of right heart failure before reaching the end of the experimental protocol. Remodeling of precapillary resistance vessels is evident histologically by the marked media hypertrophy in these vessels and by quantitative morphometric analysis.

For chronic sildenafil treatment, we started the therapeutic intervention when the development of pulmonary hypertension had already commenced, from Week 2 to Week 4, which is in contrast to most previous investigations in this model, in which the MCT and the agent of interest were coapplied (e.g., endothelin-antagonist [28], prostaglandin E1 [29], or E4010 [30]). In spite of delayed administration, significant attenuation of pulmonary hypertension evolving in response to the pyrrolizidine was noted. This was obvious from the lower values of systolic pulmonary artery pressure and pulmonary vascular resistance obtained on catheterization of these animals as well as the extent of right heart hypertrophy. Concomitantly, arterial oxygenation improved, accompanied by an increase in central venous oxygen saturation, although the cardiac index did not substantially increase. It has to be kept in mind that these measurements addressed only baseline hemodynamics. As known from patients with pulmonary hypertension, a decrease in pulmonary vascular resistance may allow one to respond more adequately with cardiac index increase to exercise, even if baseline cardiac index is unchanged (31, 32). Moreover, better coping with pulmonary hypertensive crises might be expected. Thus, although baseline cardiac index did not change in response to sildenafil treatment, the significant reduction of pulmonary vascular resistance index may translate into a survival benefit in these animals, as being observed. The systemic arterial pressure was fully maintained. The extent of the pulmonary vascular resistance decrease after 2 weeks of sildenafil treatment and the profile of changes (no systemic arterial pressure decline) strongly suggest that beyond its acute vasodilatory efficacy the PDE5 inhibitor exerted an antiremodeling effect in the pulmonary circulation of the MCT-treated animals. This view is also supported by the histologic demonstration of reduced medial thickening of the precapillary lung arteries under sildenafil and the significant reduction of fully muscularized peripheral pulmonary arteries. This phenomenon has been described most recently in hypoxia-induced pulmonary hypertension in rats (33). These findings are of interest as two independent studies, which investigated long-term inhalation of nitric oxide in MCT-treated rats, did not observe beneficial effects under these conditions (34, 35). Thus, the sildenafil mode of action appears to exceed the efficacy of nitric oxide in this model, which may be due to the fact that this PDE5 inhibitor also amplifies nitric oxide–independent cGMP-linked effects, such as those forwarded by natriuretic peptides. Moreover, cross-stabilization of cAMP or cyclic nucleotide unrelated effects of sildenafil might be involved. It is of interest that markedly enhanced cGMP levels were demonstrated in MCT-treated rats fed with E4010, another PDE5 inhibitor, although no hemodynamic measurements were undertaken in this previous study (30). We found similar levels of plasma cGMP under basal conditions and MCT treatment, and it is of interest that under sildenafil treatment we did not reach such high levels as in E4010-treated rats but similar effects on mortality and right heart hypertrophy, even when therapy was started after the development of pulmonary hypertension.

Clear efficacy of sildenafil was also demonstrated when this agent was employed as "rescue" therapy from Days 28–42, after a 4-week period of full establishment of MCT-induced pulmonary hypertension. A significant inhibition of progression (right ventricular systolic pressure, RV/LV + S) was noted. After 42 days, the pulmonary vascular resistance values of the sildenafil-treated animals were below those of the MCT42 control animals and below those of the MCT28 control subjects. Moreover, survival of the MCT42/Sil28–42 rats surpassed that of the MCT42 animals. This observation is in line with the previous report that the PDE5 inhibitor E4010 reduced mortality of MCT-treated rats when coadministered with the alkaloid (30).

Finally, the gelatinases MMP-2 and MMP-9 were found to be downregulated in the sildenafil-treated groups. These matrix metalloproteinases are linked to proliferation and migration of vascular cells, and it has been shown recently that both MMPs are downregulated in response to the stable cGMP analogue 8-bromo-cGMP or the nitric oxide-donor NONOate (36). These findings further support the view that sildenafil exerts a substantial antiproliferative effect in the MCT model.

When performing long-term feeding with sildenafil, the development of vascular remodeling and right heart hypertrophy in response to MCT was attenuated, with preservation of gas exchange and systemic arterial pressure. Further efficacy was demonstrated when this PDE5 inhibitor was employed for late therapeutic intervention after full establishment of the pulmonary vascular abnormalities. Although these studies were undertaken in an experimental model, which may not be predictive of response to therapy in humans, the results suggest that sildenafil may be useful for antiremodeling therapy in patients with pulmonary hypertension.


   Acknowledgments
 
R.T.S. has no declared conflict of interest; K.P.K. has no declared conflict of interest; H.A.G. has no declared conflict of interest; H.Y. has no declared conflict of interest; G.B. has had full employment in Pfizer research and development for 11 years; L.E. has no declared conflict of interest; M.E. has no declared conflict of interest; N.W. has no declared conflict of interest; F.R. has no declared conflict of interest; A.G. has no declared conflict of interest; D.W. has no declared conflict of interest; W.S. has no declared conflict of interest; F.G. has no declared conflict of interest.

The authors thank Prof. Dr. R. L. Snipes for thorough linguistic editing of the manuscript and Karin Quanz for technical assistance and measurement of cGMP.


   FOOTNOTES
 
Supported by the Deutsche Forschungsgemeinschaft (SFB 547, Project C6).

Received in original form February 26, 2003; accepted in final form September 3, 2003


   REFERENCES
TOP
 ABSTRACT
 METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. D'Alonzo GE, Barst RJ, Ayres SM, Bergofsky EH, Brundage BH, Detre KM, Fishman AP, Goldring RM, Groves BM, Kernis JT. Survival in patients with primary pulmonary hypertension: results from a national prospective registry. Ann Intern Med 1991;115:343–349.
  2. Lee P, Langevitz P, Alderdice CA, Aubrey M, Baer PA, Baron M, Buskila D, Dutz JP, Khostanteen I, Piper S. Mortality in systemic sclerosis (scleroderma). Q J Med 1992;82:139–148.
  3. Prasad S, Wilkinson J, Gatzoulis MA. Sildenafil in primary pulmonary hypertension. N Engl J Med 2000;343:1342.[Free Full Text]
  4. Wilkens H, Guth A, Konig J, Forestier N, Cremers B, Hennen B, Bohm M, Sybrecht GW. Effect of inhaled iloprost plus oral sildenafil in patients with primary pulmonary hypertension. Circulation 2001;104:1218–1222.[Abstract/Free Full Text]
  5. Ghofrani HA, Wiedemann R, Rose F, Olschewski H, Schermuly RT, Weissmann N, Seeger W, Grimminger F. Combination therapy with oral sildenafil and inhaled iloprost for severe pulmonary hypertension. Ann Intern Med 2002;136:515–522.[Abstract/Free Full Text]
  6. Ghofrani HA, Wiedemann R, Rose F, Schermuly RT, Olschewski H, Weissmann N, Gunther A, Walmrath D, Seeger W, Grimminger F. Sildenafil for treatment of lung fibrosis and pulmonary hypertension: a randomised controlled trial. Lancet 2002;360:895–900.[CrossRef][Medline]
  7. Abrams D, Schulze-Neick I, Magee AG. Sildenafil as a selective pulmonary vasodilator in childhood primary pulmonary hypertension. Heart 2000;84:E4.
  8. Lepore JJ, Maroo A, Pereira NL, Ginns LC, Dec GW, Zapol WM, Bloch KD, Semigran MJ. Effect of sildenafil on the acute pulmonary vasodilator response to inhaled nitric oxide in adults with primary pulmonary hypertension. Am J Cardiol 2002;90:677–680.[CrossRef][Medline]
  9. Michelakis E, Tymchak W, Lien D, Webster L, Hashimoto K, Archer S. Oral sildenafil is an effective and specific pulmonary vasodilator in patients with pulmonary arterial hypertension: comparison with inhaled nitric oxide. Circulation 2002;105:2398–2403.[Abstract/Free Full Text]
  10. Shekerdemian LS, Ravn HB, Penny DJ. Intravenous sildenafil lowers pulmonary vascular resistance in a model of neonatal pulmonary hypertension. Am J Respir Crit Care Med 2002;165:1098–1102.[Abstract/Free Full Text]
  11. Goldenberg MM. Safety and efficacy of sildenafil citrate in the treatment of male erectile dysfunction. Clin Ther 1998;20:1033–1048.[CrossRef][Medline]
  12. Walker DK, Ackland MJ, James GC, Muirhead GJ, Rance DJ, Wastall P, Wright PA. Pharmacokinetics and metabolism of sildenafil in mouse, rat, rabbit, dog and man. Xenobiotica 1999;29:297–310.[CrossRef][Medline]
  13. Torphy TJ. Phosphodiesterase isozymes: molecular targets for novel antiasthma agents. Am J Respir Crit Care Med 1998;157:351–370.
  14. Giordano D, De Stefano ME, Citro G, Modica A, Giorgi M. Expression of cGMP-binding cGMP-specific phosphodiesterase (PDE5) in mouse tissues and cell lines using an antibody against the enzyme amino- terminal domain. Biochim Biophys Acta 2001;1539:16–27.[Medline]
  15. Hanson KA, Burns F, Rybalkin SD, Miller JW, Beavo J, Clarke WR. Developmental changes in lung cGMP phosphodiesterase-5 activity, protein, and message. Am J Respir Crit Care Med 1998;158:279–288.
  16. Black SM, Sanchez LS, Mata-Greenwood E, Bekker JM, Steinhorn RH, Fineman JR. sGC and PDE5 are elevated in lambs with increased pulmonary blood flow and pulmonary hypertension. Am J Physiol Lung Cell Mol Physiol 2001;281:L1051–L1057.[Abstract/Free Full Text]
  17. MacLean MR, Johnston ED, Mcculloch KM, Pooley L, Houslay MD, Sweeney G. Phosphodiesterase isoforms in the pulmonary arterial circulation of the rat: changes in pulmonary hypertension. J Pharmacol Exp Ther 1997;283:619–624.[Abstract/Free Full Text]
  18. Murray F, MacLean MR, Pyne NJ. Increased expression of the cGMP-inhibited cAMP-specific (PDE3) and cGMP binding cGMP-specific (PDE5) phosphodiesterases in models of pulmonary hypertension. Br J Pharmacol 2002;137:1187–1194.[CrossRef][Medline]
  19. Clapp LH, Finney P, Turcato S, Tran S, Rubin LJ, Tinker A. Differential effects of stable prostacyclin analogs on smooth muscle proliferation and cyclic AMP generation in human pulmonary artery. Am J Respir Cell Mol Biol 2002;26:194–201.[Abstract/Free Full Text]
  20. Huxtable RJ. Activation and pulmonary toxicity of pyrrolizidine alkaloids. Pharmacol Ther 1990;47:371–389.[CrossRef][Medline]
  21. Rosenberg HC, Rabinovitch M. Endothelial injury and vascular reactivity in monocrotaline pulmonary hypertension. Am J Physiol 1988;255:H1484–H1491.
  22. Schermuly RT, Kreisselmeier KP, Yilmaz H, Butrous G, Samidurai A, Pullamsetti S, Ermert L, Weissmann N, Rose F, Walmrath D, et al. Chronic sildenafil treatment inhibits monocrotaline-induced pulmonary hypertension and right heart hypertrophy [abstract]. Am J Respir Crit Care Med 2003;167:A824.
  23. Schermuly RT, Weissmann N, Enke B, Ghofrani HA, Forssmann WG, Grimminger F, Seeger W, Walmrath D. Urodilatin, a natriuretic peptide stimulating particulate guanylate cyclase, and the phosphodiesterase 5 inhibitor dipyridamole attenuate experimental pulmonary hypertension: synergism upon coapplication. Am J Respir Cell Mol Biol 2001;25:219–225.[Abstract/Free Full Text]
  24. Rabinovitch M, Gamble WJ, Miettinen OS, Reid L. Age and sex influence on pulmonary hypertension of chronic hypoxia and on recovery. Am J Physiol 1981;240:H62–H72.
  25. Wilson DW, Segall HJ, Pan LC, Lame MW, Estep JE, Morin D. Mechanisms and pathology of monocrotaline pulmonary toxicity. Crit Rev Toxicol 1992;22:307–325.[Medline]
  26. Cowan KN, Heilbut A, Humpl T, Lam C, Ito S, Rabinovitch M. Complete reversal of fatal pulmonary hypertension in rats by a serine elastase inhibitor. Nat Med 2000;6:698–702.[CrossRef][Medline]
  27. Ono S, Voelkel NF. PAF antagonists inhibit monocrotaline-induced lung injury and pulmonary hypertension. J Appl Physiol 1991;71:2483–2492.[Abstract/Free Full Text]
  28. Prie S, Leung TK, Cernacek P, Ryan JW, Dupuis J. The orally active ET(A) receptor antagonist (+)-(S)-2-(4,6-dimethoxy- pyrimidin-2-yloxy)-3-methoxy-3,3-diphe nyl-propionic acid (LU 135252) prevents the development of pulmonary hypertension and endothelial metabolic dysfunction in monocrotaline-treated rats. J Pharmacol Exp Ther 1997;282:1312–1318.[Abstract/Free Full Text]
  29. Sakuma F, Miyata M, Kasukawa R. Suppressive effect of prostaglandin E1 on pulmonary hypertension induced by monocrotaline in rats. Lung 1999;177:77–88.[CrossRef][Medline]
  30. Kodama K, Adachi H. Improvement of mortality by long-term E4010 treatment in monocrotaline-induced pulmonary hypertensive rats. J Pharmacol Exp Ther 1999;290:748–752.[Abstract/Free Full Text]
  31. Blumberg FC, Riegger GA, Pfeifer M. Hemodynamic effects of aerosolized iloprost in pulmonary hypertension at rest and during exercise. Chest 2002;121:1566–1571.[Abstract/Free Full Text]
  32. Castelain V, Chemla D, Humbert M, Sitbon O, Simonneau G, Lecarpentier Y, Herve P. Pulmonary artery pressure-flow relations after prostacyclin in primary pulmonary hypertension. Am J Respir Crit Care Med 2002;165:338–340.[Abstract/Free Full Text]
  33. Sebkhi A, Strange JW, Phillips SC, Wharton J, Wilkins MR. Phosphodiesterase type 5 as a target for the treatment of hypoxia-induced pulmonary hypertension. Circulation 2003;107:3230–3235.[Abstract/Free Full Text]
  34. Horstman DJ, Frank DU, Rich GF. Prolonged inhaled NO attenuates hypoxic, but not monocrotaline-induced, pulmonary vascular remodeling in rats. Anesth Analg 1998;86:74–81.[Abstract]
  35. Maruyama J, Maruyama K, Mitani Y, Kitabatake M, Yamauchi T, Miyasaka K. Continuous low-dose NO inhalation does not prevent monocrotaline-induced pulmonary hypertension in rats. Am J Physiol 1997;272:H517–H524.
  36. Gurjar MV, Sharma RV, Bhalla RC. eNOS gene transfer inhibits smooth muscle cell migration and MMP-2 and MMP-9 activity. Arterioscler Thromb Vasc Biol 1999;19:2871–2877.[Abstract/Free Full Text]



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