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(Circulation. 2004;110:3306-3312.)
© 2004 American Heart Association, Inc.

Coronary Heart Disease

Overexpression of Brain Natriuretic Peptide Facilitates Neutrophil Infiltration and Cardiac Matrix Metalloproteinase-9 Expression After Acute Myocardial Infarction

Rika Kawakami, MD; Yoshihiko Saito, MD, PhD; Ichiro Kishimoto, MD, PhD; Masaki Harada, MD, PhD; Koichiro Kuwahara, MD, PhD; Nobuki Takahashi, MD; Yasuaki Nakagawa, MD; Michio Nakanishi, MD; Keiji Tanimoto, MD; Satoru Usami, MD; Shinji Yasuno, MD; Hideyuki Kinoshita, MD; Hideki Chusho, MD, PhD; Naohisa Tamura, MD, PhD; Yoshihiro Ogawa, MD, PhD; Kazuwa Nakao, MD, PhD

From the Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, Kyoto, Japan. Dr Saito is now at the First Department of Internal Medicine, Nara Medical University, Nara, Japan.

Correspondence to Ichiro Kishimoto, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka, 565-8565, Japan. E-mail kishimot{at}ri.ncvc.go.jp

Received January 4, 2004; de novo received June 8, 2004; accepted July 7, 2004.

	Abstract

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Background— Recent clinical trials have shown that systemic infusion of nesiritide, a recombinant human brain natriuretic peptide (BNP), improves hemodynamic parameters in acutely decompensated hearts. This suggests that BNP exerts a direct cardioprotective effect and might thus be a useful therapeutic agent with which to treat acute myocardial infarction (MI). In the present study, we used BNP-transgenic (BNP-Tg) mice with elevated plasma BNP to determine whether and how BNP contributes to left ventricular remodeling and healing after MI.

Methods and Results— We examined the accumulation of neutrophils and the expression and activation of matrix metalloproteinase (MMP)-9 in the ventricles of male BNP-Tg mice and their nontransgenic (non-Tg) littermates during the early phase after acute MI. The numbers of neutrophils infiltrating the infarcted area were significantly increased in BNP-Tg mice 3 days after MI. In addition, both the gene expression and zymographic activity of MMP-9, but not MMP-2, were significantly higher in BNP-Tg than non-Tg mice. Double immunostaining revealed that neutrophils are the main source of the MMP-9, although doxycycline, an MMP inhibitor, had no effect on neutrophil infiltration of the infarcted area in BNP-Tg mice.

Conclusions— These results demonstrate that elevated plasma BNP facilitates neutrophil infiltration of the infarcted area after MI and increases the activity of the MMP-9 they produce. This suggests that BNP plays a key role in the processes of extracellular matrix remodeling and wound-healing during the early phase after acute MI.

Key Words: metalloproteinases • myocardial infarction • natriuretic peptides • remodeling • neutrophils

	Introduction

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By secreting both atrial and brain natriuretic peptides (ANP and BNP, respectively), which act via natriuretic peptide receptor A (NPRA) to induce natriuresis, diuresis, and vasodilation and to inhibit the renin-angiotensin-aldosterone and sympathetic nervous systems, the heart serves as an important endocrine organ involved in the regulation of blood pressure and fluid-electrolyte balance.^1,2 ANP is synthesized and secreted primarily from the atria in adult mammals, whereas BNP is secreted primarily from the ventricle.³ Synthesis and secretion of both ANP and BNP are markedly increased in patients with congestive heart failure.⁴ Plasma BNP levels are also strongly increased during the early phase of acute myocardial infarction (MI), although plasma ANP levels are increased only slightly.⁵ Such sustained increases in plasma BNP are correlated with enlargement of the left ventricle (LV), decreased ventricular contractility, and increased ventricular stiffness,^6,7 which suggests that BNP might play a significant role in ventricular remodeling. In fact, using BNP-deficient mice, we previously showed that endogenous BNP is a local regulator of ventricular fibrosis.⁸

Intravenous infusion of nesiritide, a recombinant human BNP, was recently reported to have beneficial hemodynamic effects in patients with decompensated congestive heart failure.^9,10 In addition to alleviating cardiac preload and afterloads, BNP might exert a direct cardioprotective effect^11,12 that could prevent LV remodeling after MI. The effects of continuously high levels of BNP on the infarcted myocardium are unknown, however. We therefore used BNP-transgenic (BNP-Tg) mice to investigate the effects of sustained increases in plasma BNP on cardiac repair pathways and remodeling after MI. These mice overexpress the BNP in their livers and show a >100-fold increase in plasma BNP levels throughout their lives.^13,14 In the present study, we focused on leukocyte infiltration, the genetic regulation of myocardial collagen synthesis including transforming growth factor (TGF)-ß, and the activity of matrix metalloproteinase (MMP)-9, an important regulatory enzyme involved in extracellular matrix (ECM) degradation and cell migration during cardiac wound healing,^15,16 in infarcted BNP-Tg hearts.

	Methods

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Experimental Animals
BNP-Tg mice were developed as previously described¹³ by use of the liver-specific human serum amyloid P component promoter. These mice show plasma BNP concentrations that are at least 2 orders of magnitude higher than those of their wild-type littermates, C57BL/6J nontransgenic (non-Tg) mice. Acute MI was induced in male BNP-Tg (n=51) and non-Tg (n=43) mice (age, 8 to 12 weeks; weight, 25 to 30 g) by ligation of the left coronary artery.^17,18 The same procedure without coronary artery ligation served as the sham operation. The experimental animals were monitored for 7 days after MI had been induced.

Echocardiography
Echocardiography was performed under light anesthesia with a mixture of ketamine (80 mg/kg) and xylazine (4 mg/kg) and spontaneous respiration.¹⁹

Hemodynamic and Infarct Size Measurements
After 3 days, a 2F Millar Micro-Tip catheter transducer (Millar Instruments) was inserted into the right carotid artery and then advanced into the LV for recording of LV systolic pressure, LV end-diastolic pressure, and LV maximum and minimum rates of pressure development (dP/dt). The ventricles were excised after evaluation of hemodynamic parameters. Infarct size was expressed as the ratio of the infarct to total LV mass as previously described.¹⁷

Immunohistochemistry and Quantitative Analysis of Histology
In a subset of animals (6 BNP-Tg and 6 non-Tg), the LV was cut into 3 transverse sections (apex, middle ring, and base) 3 days after MI. Immunostaining was then performed on frozen tissue specimens (6 µm) with rat anti-mouse 7/4 antibody (Serotec), which recognizes a polymorphic 40-kDa antigen expressed by neutrophils, and goat anti-mouse MMP-9 antibody (Santa Cruz Biotechnology). For each section, neutrophil 7/4-positive cells were counted in the infarcted area in at least 8 to 10 randomly selected high-power fields by use of a computer program (KS400 Version 3.00; Carl Zeiss).

Myeloperoxidase Activity Assay
Myeloperoxidase (MPO) activity was measured spectrophotometrically at 460 nm in 50 mmol/L phosphate buffer (pH 6.0) containing 0.167 mg/mL o-dianisidine hydrochloride (Sigma) and 0.0005% hydrogen peroxide as described previously.²⁰ One unit of MPO was defined as the quantity of enzyme needed to hydrolyze peroxide at a rate of 1 mmol/min at 25°C.

Northern Blot Analysis
Northern blots were made using 20 µg of total RNA isolated from frozen LV tissue by use of a technique described in detail elsewhere.⁸ The probes for collagen I, collagen III, TGF-ß₁, TGF-ß₃, fibronectin and BNP were already available to us.⁸ The other cDNA probes were prepared using reverse transcription–polymerase chain reaction with primers based on the published sequences.

Zymographic Measurement of Gelatinase Activity
MMP activity in 30 µg of myocardial extract was measured by gelatin zymography as previously described.^21,22 The gelatinolytic zones were quantified by use of NIH 1.62 image analysis software.²²

Type IV Collagenase Activity Assay
The activity of type IV collagenases (MMP-2 and MMP-9) was assessed by use of a commercially available kit (Yagai Research Center) according to the manufacturer’s instructions.²³

Treatment With Doxycycline
In the doxycycline study, mice receiving 60 mg/kg doxycycline per day by gavage were compared with an untreated control group. Administration of doxycycline was started 3 days before induction of experimental MI and continued for 7 days after MI.

Data Analysis
All results are reported as mean±SEM. Two-way ANOVA followed by Tukey-Kramer tests was used to evaluate the effects of MI and genotype. The mortality data (deaths during the 7-day protocol, including causes of death) were analyzed by use of the ² test. Values of P<0.05 were considered significant.

	Results

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Infarct Size, Echocardiography, and Hemodynamics
Three days after left coronary artery ligation, the sizes of the resultant infarcts were similar in BNP-Tg and non-Tg mice (BNP-Tg, 42.2±3.7% versus non-Tg, 40.4±3.8%; P=0.75, n=7). To evaluate the effect of a high plasma BNP concentration on the performance of the infarcted heart, we assessed cardiac function and LV geometry by use of echocardiography. The Table shows that the increase in LV chamber size and the noninfarcted wall thickness were the same in BNP-Tg and non-Tg mice 3 days after MI. LV systolic pressure measured by use of a Millar catheter was lower in sham-operated BNP-Tg mice than in sham-operated non-Tg mice (Table), which is consistent with our earlier observation that systolic blood pressure measured by use of the tail-cuff method was 20 mm Hg lower in BNP-Tg than non-Tg mice.¹³ Conversely, there was no significant difference in LV systolic pressure, LV end-diastolic pressure, LV +dP/dt_max, or –dP/dt_min between the 2 groups after ligation. We did, however, note a trend toward improved hemodynamic and echocardiographic parameters in BNP-Tg mice, although it did not reach statistical significance.

View this table: [in this window] [in a new window]   Echocardiographic and Hemodynamic Data

Infarct Infiltration by Neutrophils
Accumulation of leukocytes in the infarcted region is thought to be one step in the process of wound repair.^16,24 We therefore counted the leukocytes infiltrating the infarcted region after MI by use of a neutrophil-specific antibody. Neutrophils were identified throughout the infarcted segments after MI (Figure 1a). Moreover, although quantitative analysis of images of the infarcted region obtained 3 days after MI showed that their numbers increased in both BNP-Tg and non-Tg mice, there were significantly greater numbers of neutrophils in BNP-Tg than non-Tg hearts (BNP-Tg, 415.41±12.90 cells/mm² versus non-Tg, 330.70±16.82 cells/mm²; P<0.01, n=6; Figure 1b).

View larger version (71K): [in this window] [in a new window]   Figure 1. Accumulation of neutrophils in hearts of infarcted mice. a, Representative micrograph showing stained neutrophils within infarcted region (magnification x200). b, Numbers of neutrophils per mm2 within infarcted area 3 days after MI (n=6 for each). c, Cardiac MPO activity expressed as units/100 mg tissue wet wt in sham-operated and infarcted mice 3 days after MI (n=8 for each). Values are mean±SEM; *P<0.01 vs non-Tg mice with MI.

To further assess neutrophil accumulation in the infarcted areas, we also measured MPO activity. As shown in Figure 1c, cardiac MPO activity was significantly higher in BNP-Tg than non-Tg mice 3 days after MI (BNP-Tg, 2.80±0.40 U/100 mg tissue versus non-Tg, 1.33±0.23 U/100 mg tissue; n=8 to 10, P<0.01), whereas there was no difference between the sham-operated groups.

Taken together, the data presented in this section clearly indicate that within 3 days after MI, neutrophils accumulate to a significantly greater degree in the infarcted regions of BNP-Tg hearts than non-Tg hearts.

Cardiac Gene Expression in Infarcted Hearts
Recent evidence highlights the involvement of the plasminogen activator–metalloproteinase system in myocardial neutrophil accumulation, the repair processes, and the rupture seen after MI.^15,16 When we examined gene expression of plasminogen activators and MMPs 3 days after MI, we found that, with the exception of GAPDH, transcription of all the genes examined was upregulated compared with sham-operated animals. In addition, expression of MMP-9 mRNA was significantly higher in BNP-Tg than non-Tg mice after ligation (Figure 2, a and b), whereas there was no difference in the expression of MMP-2, TIMP-1, urokinase-type plasminogen activator, and plasminogen activator inhibitor-1 mRNA in the 2 MI groups.

View larger version (71K): [in this window] [in a new window]   Figure 2. a, Representative autoradiograms showing Northern blot analysis in hearts harvested from sham-operated and infarcted mice 3 days after MI. b, Summary of results obtained from Northern blot analyses; mRNA levels in sham-operated non-Tg hearts were assigned a value of 1.0. Values are mean±SEM; *P<0.05 vs non-Tg mice with MI.

We also focused on the synthetic processes involved in collagen turnover by examining the expression of mRNAs encoding TGF-ß₁, TGF-ß₃, collagen I, and collagen III, which are known to be involved in cardiac fibroblast proliferation and the biosynthesis of ECM proteins.^25–27 We found that their expression was similarly upregulated in the infarcted regions of both BNP-Tg and non-Tg hearts (Figure 2, a and b), indicating that overexpression of BNP does not affect the biosynthesis of collagen during the early phase of acute MI.

Increased MMP Activity in Infarcted Hearts
We next used gelatin zymography to evaluate the extent to which overexpression of BNP affects MMP-9 enzymatic activity. As shown in Figure 3a, the gelatinase activity of MMP-9, but not MMP-2, was significantly (P<0.05) elevated in infarcted BNP-Tg hearts compared with infarcted non-Tg hearts. Likewise, type IV collagenase activity was significantly higher in infarcted BNP-Tg than non-Tg hearts (BNP-Tg, 0.399±0.037 U/100 mg wet wt versus non-Tg, 0.300±0.017 U/100 mg wet wt; n=7, P<0.05; Figure 3b). Because MMP-9 and -2 are the 2 major collagenases that degrade type IV collagen²³ and zymography showed that there was no difference in MMP-2 activity within the infarcts of BNP-Tg and non-Tg mice, the increased digestion of type IV collagen in BNP-Tg hearts is attributable to the increase in MMP-9 activity.

View larger version (32K): [in this window] [in a new window]   Figure 3. a, Top, Representative gelatin zymography performed 3 days after MI (n=6 for each); a mixture of human MMP-2 and pro-MMP-9 served as a standard (std). Bottom, densitometric analysis of MMP-9 abundance. b, Cardiac type IV collagenase activity expressed as units/100 mg tissue wet weight 3 days after MI (n=7 for each). Values are mean±SEM; *P<0.05 vs non-Tg mice with MI.

Neutrophils Are the Predominant Source of MMP-9
We then evaluated the distribution of the MMP-9 by using confocal fluorescence microscopy to visualize the double immunostaining of MMP-9 (green) and neutrophils (red) in thin sections of frozen mouse LV. Three days after MI, immunoreactive MMP-9 and neutrophils were detected within the infarcted myocardium and the border regions in both BNP-Tg and non-Tg hearts (Figure 4, a–d). Moreover, the double labeling revealed that the distribution of immunoreactive neutrophils overlapped that of MMP-9 (Figure 4, e and f), indicating that the major source of MMP-9 is the neutrophils infiltrating the infarcted region. By contrast, MMP-9 levels were negligible in the sham-operated mice and the noninfarcted regions of the infarcted mice (data not shown).

View larger version (29K): [in this window] [in a new window]   Figure 4. Confocal images of double immunostaining for MMP-9 and neutrophil 7/4. Immunostaining and cellular localization of MMP-9 within infarcted hearts of BNP-Tg (right) and non-Tg (left) mice 3 days after MI. Images show single immunostaining for MMP-9 (green) (a and b) and neutrophil 7/4 (red) (c and d). Double immunostaining (yellow) shows colocalization of MMP-9 within 7/4-stained neutrophils in infarcted region after MI (e and f). Magnification x400.

MMP-9 Inhibition Did Not Affect Neutrophil Infiltration in BNP-Tg
Finally, we assessed the functional significance of MMPs in BNP-Tg mice subjected to experimental MI by treating the mice with doxycycline, a nonselective MMP inhibitor. We found that the numbers of neutrophils detected by use of anti-mouse neutrophil 7/4 antibody were similarly increased in control BNP-Tg and doxycycline-treated BNP-Tg mice (control BNP-Tg, 428.24±29.84 cells/mm² versus doxycycline-treated BNP-Tg, 432.93±23.86 cells/mm²; P=0.90, n=6; Figure 5, a and b). Likewise, there were no significant differences in the cardiac MPO activity in control BNP-Tg and doxycycline-treated BNP-Tg mice (control BNP-Tg, 3.03±0.36 U/100 mg tissue versus doxycycline-treated BNP-Tg, 2.80±0.32 U/100 mg tissue; P=0.63; Figure 5c). Thus, the increased infiltration of neutrophils into the infarcted area was not dependent on increased MMP-9 activity in the neutrophils themselves.

View larger version (77K): [in this window] [in a new window]   Figure 5. Accumulation of neutrophils within infarcted regions of control BNP-Tg and doxycycline-treated BNP-Tg mice. a, Representative micrograph showing stained neutrophils within infarct area (magnification x200). b, Numbers of neutrophils per mm2 within infarcted area 3 days after MI (n=6 for each). Values are shown as mean±SEM; NS, not significant. c, Cardiac MPO activity expressed as units/100 mg tissue wet weight in sham-operated (n=3 for each), untreated infarcted (n=18), and doxycycline-treated infarcted BNP-Tg mice (n=17). Values are mean±SEM; *P<0.01 vs sham values.

	Discussion

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We previously showed that plasma BNP levels are greatly elevated in patients with acute MI; they reach a peak within 24 hours after onset, then decline and increase again to a second peak over the next 3 to 7 days.⁵ Thus, high plasma BNP levels persist during the period when neutrophils and other inflammatory cells infiltrate the infarcted area. In the present study, we used BNP-Tg mice to assess the effects of a pharmacological dose of BNP on the myocardium early after acute MI. We found that (1) there is a greater accumulation of neutrophils in BNP-Tg hearts; (2) gene expression and enzyme activity of MMP-9 are higher in BNP-Tg hearts; (3) the major source of MMP-9 is the neutrophils infiltrating the infarcted region of BNP-Tg hearts; and (4) doxycycline, a potent MMP inhibitor, has no effect on the increased infiltration of neutrophils into the infarcted area in BNP-Tg mice.

The wound repair process involves temporally overlapping phases that include inflammation, new tissue formation, and tissue remodeling.²⁸ During the inflammatory phase, collagen and other ECM components may be degraded as a result of increased MMP activity.^29,30 In the present study, we found that early after MI, neutrophil infiltration of the infarcted area is augmented in BNP-Tg mice, and that there are corresponding increases in MMP-9 expression and activity associated with the infiltrating neutrophils. By contrast, there were no significant changes in the levels of TGF-ß₁, TGF-ß₃, collagen I, collagen III, or fibronectin mRNA, which suggests that overexpression of BNP leads to exaggerated collagen degradation by MMP-9 produced by neutrophils without an apparent increase in synthesis. Moreover, the fact that the increase in zymographic MMP-9 activity in BNP-Tg mice appeared to be more pronounced than the increase in neutrophil number suggests that BNP may have a direct effect on the amount of MMP-9 activity produced by each activated neutrophil. This idea is supported by the results of supplemental experiments showing that in the presence of the neutrophil-activating factor formyl-methionyl-leucyl-phenylalanine (fMLP; 10^–7 mol/L), ANP (10^–8 mol/L), which shares its receptor (NPRA) with BNP and is equally potent, elicited a 2.1-fold increase (P<0.01) in the transcription and activation of MMP-9 in human neutrophils.

We also tested whether upregulation of MMP-9 contributes to the accumulation of neutrophils in BNP-Tg mice. On the basis of evidence that it suppresses the activity of such MMPs as collagenase, gelatinase, and stromelysin both directly and indirectly,³¹ we used doxycycline to evaluate the extent to which elevated MMP production is involved in neutrophil accumulation within the infarcted regions of BNP-Tg hearts. That we found no difference in the neutrophil accumulation in control BNP-Tg and doxycycline-treated BNP-Tg mice suggests that the increased MMP-9 activity is most likely not responsible for the neutrophil accumulation in BNP-Tg animals. Conversely, one possible explanation for the increased leukocyte infiltration is that BNP exerts a direct effect on neutrophil chemotaxis. In fact, a recent study has shown that ANP affects human neutrophil migration at concentrations ranging from 4x10^–9 to 10^–7 mol/L.³² The plasma BNP concentration in BNP-Tg mice was approximately 3x10^–9 mol/L, which is comparable to the effective ANP concentration reported earlier, because ANP and BNP act via NPRA with equal potency. Another possible explanation is an indirect effect via endothelial adhesion molecules. We previously showed that the diminished neutrophil accumulation seen during ischemia/reperfusion in NPRA-deficient mice is probably a result of suppressed expression of P-selectin in coronary endothelial cells and that ANP upregulates P-selectin expression in cultured endothelial cells exposed to oxidative stress.²⁰ Thus, BNP might increase neutrophil accumulation by upregulating one or more of the endothelial adhesion molecules that tether circulating neutrophils to the endothelium.

Heymans et al¹⁶ recently showed that MMP-9 deficiency retards the wound healing process after MI in mice, which increases the size of residual necrotic areas. In the same study, these investigators also showed that the lack of MMP-9 proteolytic activity results in almost complete protection against infarct rupture. These results suggest that MMP-9 is a key regulator of infarct healing and rupture, acting via degradation of ECM early after acute MI. Indeed, BNP-Tg mice tended to die of cardiac rupture more frequently than non-Tg mice: among the dead mice (26 BNP-Tg and 9 non-Tg), 47.1% (n=24) of the BNP-Tg mice died of cardiac rupture after MI, whereas 18.6% (n=2) of non-Tg mice died of the same cause (P=0.75 by ² analysis). Moreover, although the effect did not reach statistical significance, doxycycline tended to attenuate cardiac rupture in BNP-Tg mice, suggesting that elevated MMP-9 activity may be involved. However, because the level of collagen and TGF-ß expression is lower in sham-operated BNP-Tg hearts than in sham-operated non-Tg hearts (Figure 2), the apparent high frequency of cardiac rupture in BNP-Tg mice might be attributable to a reduction in collagen matrix in BNP-Tg mice. More importantly, the transient activation of MMP-9 induced by BNP may speed up infarct healing and modulate the overall late remodeling process. In fact, at 6 weeks after ligation, LV dilatation and hypertrophy of the noninfarcted zone seen in the non-Tg mice are attenuated in BNP-Tg mice (our unpublished data). These observations suggest that transient MMP-9 expression induced by the elevation in BNP during the earliest phase after MI is a cardioprotective mechanism affecting late LV remodeling.

In summary, overexpression of BNP in mice led to neutrophil infiltration and MMP-9 expression in the infarcted region after MI, an effect that could lead to exaggerated degradation of ECM components. This suggests that BNP plays a novel role in the process of cardiac repair during the acute phase of MI.

	Acknowledgments

 
This work was supported in part by research grants from the Japanese Ministry of Education, Science, and Culture; the Japanese Ministry of Health and Welfare; and the Japanese Society for the Promotion of Science Research for the Future program (JSPS-RFTF96I00204 and JSPS-RFTF98L00801). Excellent secretarial work by K. Okamura is also acknowledged.

	Footnotes

 
The online-only Data Supplement, which contains an additional figure, can be found with this article at http://www.circulationaha.org.

	References

Top Abstract Introduction Methods Results Discussion References

 

1. De Bold AJ. Atrial natriuretic factor: a hormone produced by the heart. Science. 1985; 230: 767–770.[Abstract/Free Full Text]
   
2. Rosenzweig A, Seidman CE. Atrial natriuretic factor and related peptide hormones. Annu Rev Biochem. 1991; 60: 229–255.[CrossRef][Medline] [Order article via Infotrieve]
   
3. Mukoyama M, Nakao K, Hosoda K, et al. Brain natriuretic peptide as a novel cardiac hormone in humans: evidence for an exquisite dual natriuretic peptide system, atrial natriuretic peptide and brain natriuretic peptide. J Clin Invest. 1991; 87: 1402–1412.[Medline] [Order article via Infotrieve]
   
4. Mukoyama M, Nakao K, Saito Y, et al. Increased human brain natriuretic peptide in congestive heart failure. N Engl J Med. 1990; 323: 757–758.[Medline] [Order article via Infotrieve]
   
5. Morita E, Yasue H, Yoshimura M, et al. Increased plasma levels of brain natriuretic peptide in patients with acute myocardial infarction. Circulation. 1993; 88: 82–91.[Abstract/Free Full Text]
   
6. Yamamoto K, Burnett JC Jr, Jougasaki M, et al. Superiority of brain natriuretic peptide as a hormonal marker of ventricular systolic and diastolic dysfunction and ventricular hypertrophy. Hypertension. 1996; 28: 988–994.[Abstract/Free Full Text]
   
7. Nagaya N, Goto Y, Nishikimi T, et al. Sustained elevation of plasma brain natriuretic peptide levels associated with progressive ventricular remodelling after acute myocardial infarction. Clin Sci. 1999; 96: 129–136.[Medline] [Order article via Infotrieve]
   
8. Tamura N, Ogawa Y, Chusho H, et al. Cardiac fibrosis in mice lacking brain natriuretic peptide. Proc Natl Acad Sci U S A. 2000; 97: 4239–4244.[Abstract/Free Full Text]
   
9. Mills RM, LeJemtel TH, Horton DP, et al. Sustained hemodynamic effects of an infusion of nesiritide (human b-type natriuretic peptide) in heart failure: a randomized, double-blind, placebo-controlled clinical trial. Natrecor Study Group. J Am Coll Cardiol. 1999; 34: 155–162.[Abstract/Free Full Text]
   
10. Colucci WS, Elkayam U, Horton DP, et al. Intravenous nesiritide, a natriuretic peptide, in the treatment of decompensated congestive heart failure. Nesiritide Study Group. N Engl J Med. 2000; 343: 246–253.[Abstract/Free Full Text]
    
11. Holtwick R, van Eickels M, Skryabin BV, et al. Pressure-independent cardiac hypertrophy in mice with cardiomyocyte-restricted inactivation of the atrial natriuretic peptide receptor guanylyl cyclase-A. J Clin Invest. 2003; 111: 1399–1407.[CrossRef][Medline] [Order article via Infotrieve]
    
12. Molkentin J. A friend within the heart: natriuretic peptide receptor signaling. J Clin Invest. 2003; 111: 1275–1277.[CrossRef][Medline] [Order article via Infotrieve]
    
13. Ogawa Y, Itoh H, Tamura N, et al. Molecular cloning of the complementary DNA and gene that encode mouse brain natriuretic peptide and generation of transgenic mice that overexpress the brain natriuretic peptide gene. J Clin Invest. 1994; 93: 1911–1921.[Medline] [Order article via Infotrieve]
    
14. Chusho H, Ogawa Y, Tamura N, et al. Genetic models reveal that brain natriuretic peptide can signal through different tissue-specific receptor-mediated pathways. Endocrinology. 2000; 141: 3807–3813.[Abstract/Free Full Text]
    
15. Creemers E, Cleutjens J, Smits J, et al. Disruption of the plasminogen gene in mice abolishes wound healing after myocardial infarction. Am J Pathol. 2000; 156: 1865–1873.[Abstract/Free Full Text]
    
16. 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.[CrossRef][Medline] [Order article via Infotrieve]
    
17. Michael LH, Entman ML, Hartley CJ, et al. Myocardial ischemia and reperfusion: a murine model. Am J Physiol. 1995; 269: H2147–H2154.[Medline] [Order article via Infotrieve]
    
18. Patten RD, Aronovitz MJ, Deras-Mejia L, et al. Ventricular remodeling in a mouse model of myocardial infarction. Am J Physiol. 1998; 274: H1812–H1820.[Medline] [Order article via Infotrieve]
    
19. Ichihara S, Senbonmatsu T, Price E Jr, et al. Targeted deletion of angiotensin II type 2 receptor caused cardiac rupture after acute myocardial infarction. Circulation. 2002; 106: 2244–2249.[Abstract/Free Full Text]
    
20. Izumi T, Saito Y, Kishimoto I, et al. Blockade of the natriuretic peptide receptor guanylyl cyclase-A inhibits NF-kappaB activation and alleviates myocardial ischemia/reperfusion injury. J Clin Invest. 2001; 108: 203–213.[CrossRef][Medline] [Order article via Infotrieve]
    
21. Silvestre JS, Mallat Z, Tamarat R, et al. Regulation of matrix metalloproteinase activity in ischemic tissue by interleukin-10: role in ischemia-induced angiogenesis. Circ Res. 2001; 89: 259–264.[Abstract/Free Full Text]
    
22. Cho A, Reidy MA. Matrix metalloproteinase-9 is necessary for the regulation of smooth muscle cell replication and migration after arterial injury. Circ Res. 2002; 91: 845–851.[Abstract/Free Full Text]
    
23. Fujimura M, Gasche Y, Morita-Fujimura Y, et al. Early appearance of activated matrix metalloproteinase-9 and blood-brain barrier disruption in mice after focal cerebral ischemia and reperfusion. Brain Res. 1999; 842: 92–100.[CrossRef][Medline] [Order article via Infotrieve]
    
24. Jugdutt BI. Ventricular remodeling after infarction and the extracellular collagen matrix: when is enough enough? Circulation. 2003; 108: 1395–1403.[Free Full Text]
    
25. Weber KT, Brilla CG. Pathological hypertrophy and cardiac interstitium: fibrosis and renin- angiotensin-aldosterone system. Circulation. 1991; 83: 1849–1865.[Abstract/Free Full Text]
    
26. Butt RP, Laurent GJ, Bishop JE. Mechanical load and polypeptide growth factors stimulate cardiac fibroblast activity. Ann N Y Acad Sci. 1995; 752: 387–393.[Medline] [Order article via Infotrieve]
    
27. Cleutjens JP, Verluyten MJ, Smiths JF, et al. Collagen remodeling after myocardial infarction in the rat heart. Am J Pathol. 1995; 147: 325–338.[Abstract]
    
28. Singer AJ, Clark RA. Cutaneous wound healing. N Engl J Med. 1999; 341: 738–746.[Free Full Text]
    
29. Etoh T, Joffs C, Deschamps A, et al. Myocardial and interstitial matrix metalloproteinase activity after acute myocardial infarction in pigs. Am J Physiol. 2001; 281: H987–H994.
    
30. Tao ZY, Cavasin MA, Yang F, et al. Temporal changes in matrix metalloproteinase expression and inflammatory response associated with cardiac rupture after myocardial infarction in mice. Life Sci. 2004; 74: 1561–1572.[CrossRef][Medline] [Order article via Infotrieve]
    
31. Golub LM, Lee HM, Ryan ME, et al. Tetracyclines inhibit connective tissue breakdown by multiple non-antimicrobial mechanisms. Adv Dent Res. 1998; 12: 12–26.[Abstract/Free Full Text]
    
32. Elferink JG, De Koster BM. Atrial natriuretic factor stimulates migration by human neutrophils. Eur J Pharmacol. 1995; 288: 335–340.[CrossRef][Medline] [Order article via Infotrieve]
    

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