Published online before print April 30, 2007, doi: 10.1161/HYPERTENSIONAHA.106.084103
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
(Hypertension. 2007;50:130.)
© 2007 American Heart Association, Inc.
Original Articles |
Decreased Endogenous Levels of Ac-SDKP Promote Organ Fibrosis
From the Hypertension and Vascular Research Division (M.A.C., T.-D.L., X.-P.Y., O.A.C.), and Biostatistics and Research Epidemiology (J.J.Y.), Henry Ford Sciences Center, Henry Ford Health System, Detroit, Mich.
Correspondence to Oscar A. Carretero, Hypertension and Vascular Research Division, Henry Ford Health System, 2799 West Grand Blvd, E&R 7115, Detroit, MI 48202. E-mail ocarret1{at}hfhs.org or Maria A. Cavasin, In Vivo Pharmacology, Gilead Colorado, 7577 W 103rd Ave, Ste 212, Westminster, CO 80021. E-mail maria.cavasin@gilead.com
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionConclusionReferences |
|---|
There is convincing evidence that chronic treatment with N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), a peptide normally found in tissues and biological fluids, reduces collagen deposition in the heart and kidneys of hypertensive rats and rats with myocardial infarction. However, it is not known whether endogenous Ac-SDKP at basal concentrations has any physiological function related to collagen deposition. Prolyl oligopeptidase is responsible for release of Ac-SDKP from its precursor thymosin-ß4. When we treated rats with a specific oral rolyl oligopeptidase inhibitor, Ac-SDKP decreased significantly in the plasma, heart, and kidney. In the present study, we tested the hypothesis that endogenous Ac-SDKP at basal levels plays a physiological role, antagonizing and/or preventing excessive collagen deposition. We studied whether chronic blockade of Ac-SDKP promotes collagen accumulation and/or accelerates this process in the presence of a profibrotic stimulus such as angiotensin II. We found that decreased basal levels of Ac-SDKP increased cardiac and renal perivascular fibrosis and promoted glomerulosclerosis. Moreover, in the presence of angiotensin II decreasing basal levels of Ac-SDKP accelerated interstitial cardiac fibrosis attributable to an increase in cells that produce collagen. We concluded that Ac-SDKP participates in the regulation of collagen content under normal conditions. We believe this is the first study showing that this peptide plays a physiological role at basal concentrations, preventing organ collagen accumulation.
Key Words: prolyl endopeptidase • thymosin ß4 • angiotensin-converting enzyme • heart • kidney • collagen
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionReferences |
|---|
In hypertension and cardiovascular diseases, excessive collagen accumulation in the heart and kidney leads to pathological remodeling with important functional consequences. The net content of extracellular matrix proteins under normal conditions results from the delicate balance between synthesis and degradation.
There is convincing evidence that N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), a tetrapeptide normally present in organs and biological fluids of humans and experimental animals,1,2 can reduce collagen deposition in the heart and kidneys when it is chronically infused into hypertensive rats and rats with myocardial infarction.3–6 More recently, it has been shown to mediate the antifibrotic effects of angiotensin-converting enzyme inhibitors.7 However, it is not known whether endogenous Ac-SDKP at concentrations normally found in plasma and organs has any physiological function related to collagen deposition, especially in the heart and kidneys.
We recently found that prolyl oligopeptidase (POP), a cytosolic enzyme involved in the metabolism of many peptidic hormones and neuropeptides,8 is responsible for release of Ac-SDKP from its precursor thymosin-ß4. When we treated rats with a specific oral POP inhibitor (POPi), Ac-SDKP decreased significantly in the plasma, heart, and kidneys.9 In the present study, we tested the hypothesis that endogenous Ac-SDKP at basal levels has a physiological role, antagonizing and/or preventing excessive collagen deposition. We tested whether chronic blockade of Ac-SDKP release using a POPi promotes collagen accumulation and/or accelerates this phenomenon in the presence of a profibrotic stimulus such as angiotensin II (Ang II).
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionReferences |
|---|
Animals
The study was approved by the Institutional Animal Care and Use Committee (IACUC) of Henry Ford Health System, and all procedures were conducted in accord with the National Institutes of Health (NIH) Guide for the Care and Use of Laboratory Animals. We used 50 10-week-old male Sprague-Dawley rats (Charles River Laboratories, Wilmington, Mass). All surgical procedures were conducted with the animals under pentobarbital anesthesia (50 mg/kg, IP); and buprenorphine (0.05 mg/kg, SQ) was administered after osmotic mini-pump implantation.
Tissue Levels of Ac-SDKP, Arg8-Vasopressin, Substance-P, and Ang II
We performed a pilot study to test the effects of POPi on tissue levels of some peptides, which were reported to be POP substrates. Rats were treated with either vehicle (n=9) or POPi (n=9; S17092, 40 mg/kg per d, a gift of P. Vanhoutte, Institut de Recherches Internationales Servier, France10). POPi was mixed with peanut oil and administered daily by gavage.11 After 1 week rats were euthanized and the heart, kidneys, and brain were rapidly frozen in liquid nitrogen (LN2) and kept at –70°C until processing. We used commercially available enzyme immunoassay kits to measure Ac-SDKP (Cayman Chemicals) as well as Arg8-vasopressin and substance-P (Assay Designs) and Ang II (Peninsula Laboratories). Samples were processed according to the manufacturer’s recommendations. Tissue was weighed, homogenized with cold methanol, and centrifuged; the supernatant was evaporated to dryness and dried samples kept at –20°C until assay, when they were reconstituted with EIA buffer.
Experimental Protocol
Rats were divided into the following groups: (1) Ang II vehicle+POPi vehicle (n=8), (2) Ang II vehicle+POPi (n=9), (3) Ang II (100 µg/kg/d)+POPi vehicle (n=8), and (4) Ang II+POPi (n=9). Ang II or its vehicle (0.01N acetic acid) was infused by osmotic mini-pump implanted SQ. We used a low dose of Ang II because we did not want to reach the maximum fibrotic effect with this treatment. Systolic blood pressure was measured by tail cuff every other week. After 8 weeks, rats were euthanized, blood was collected for Ac-SDKP measurements (to ensure treatment administration), and the heart and kidneys were removed and weighed. They were cut transversely into 3 pieces: one was used for total collagen determination, the second was kept in formalin for 24 hours and then embedded in paraffin, and the third was frozen and kept in isopentane at –70°C.
Total Collagen Determinations
Total cardiac and renal collagen were measured using the established hydroxyproline (HP) method as described by Woessner.12 Briefly, tissue samples were dried, weighed, and pulverized. Each sample was hydrolyzed in 0.5 mL 6N HCl for 16 hours at 120°C. All samples were dried using a vacuum centrifuge (Savant). Dried samples were reconstituted with 1 mL distilled water and filtered using a centrifugation device with 10 kDa cutoff. HP content was determined by a color-based reaction. Results are expressed as µg HP/mg dry tissue.
Histological Determinations
All histological analyses were carried out blindly using an Olympus IX-81 inverted microscope with a digital camera equipped with Microsuite biological imaging software (Olympus America). Around 30 random fields were analyzed in each determination. To measure perivascular fibrosis (PVF) and cardiac interstitial collagen fraction, 6-µm paraffin-embedded slices from the heart and kidneys were stained using picrosirius red. Cardiac and renal PVF were expressed as the ratio of collagen to vessel cross-sectional area. Cardiac interstitial collagen fraction was calculated as a percentage of total area. To measure glomerulosclerosis, 6-µm paraffin-embedded kidney slices were stained with periodic acid-Schiff (PAS) and mesangial matrix expansion expressed as a percentage of positive PAS staining compared with total glomerular area. To assess interstitial cell proliferation and prolyl 4-hydroxylase-expressing cells, we incubated frozen heart sections with monoclonal anti-rat Ki-67 antigen antibody (1:50, clone MIB-5, Dako) and mouse anti-rat prolyl 4-hydroxylase (ß-subunit, Chemicon), respectively, at 4°C overnight, using a Vectastain ABC kit (Vector Laboratory) to visualize immunoreactivity. Sections were developed with diaminobenzidine substrate (Vector) and counterstained with hematoxylin.7 Cells were counted and expressed as cells/mm2.
Data Analysis
Three pairwise comparisons were conducted: (1) POPi versus vehicle, (2) Ang II versus vehicle, and (3) Ang II+POPi versus Ang II. The first comparison was done to test whether Ac-SDKP has any physiological role under normal conditions; the second and third comparisons were done to ascertain whether Ac-SDKP antagonizes a pro-fibrotic stimulus. Two sample t test was used for each pairwise comparison. To control the type I error rate while conducting multiple comparisons, Hochberg multiple comparison procedure was used to identify significant difference.13 The family-wise significant level was set at 0.05 and the tests with adjusted probability value less than 0.05 were considered statistical significant. All analysis results are presented as mean±SE.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionReferences |
|---|
Effect of POPi on Endogenous Levels of Ac-SDKP and Other POP Substrates: Arg8-Vasopressin, Substance-P, and Ang II
Table 1 shows amounts of these peptides in the heart, kidney, and brain (as control for the neuropeptides). Endogenous levels of Ac-SDKP decreased significantly after 1 week of chronic treatment with POPi. Ang II content was not affected by chronic POPi administration. Levels of Arg8-vasopressin and substance-P in the heart and kidneys are normally very low compared with the brain, and chronic treatment with POPi had no significant effect.
|
Effect of POPi on Cardiac and Renal Morphology and Systolic Blood Pressure in the Presence or Absence of Ang II
There were no differences in heart and kidney weight corrected by body weight between any groups (Table 2). POPi alone did not affect SBP (Figure 1A); only Ang II significantly increased SBP, and the combination of Ang II and POPi had no further effect compared with Ang II alone. Both groups treated with POPi treatment had significantly less Ac-SDKP in the heart and kidneys compared with their controls, indicating that POPi treatment was successful. Ang II infusion had no effect on organ levels of Ac-SDKP; however, it decreased plasma Ac-SDKP compared with vehicle.
|
|
Effect of POPi on Cardiac and Renal Collagen in the Presence or Absence of Ang II
Figure 1B shows total hydroxyproline content in the heart and kidneys after 8 weeks of treatment. POPi alone significantly increased total collagen content. A low dose of Ang II increased total collagen deposition slightly, and the combined treatment increased collagen content similarly to POPi alone. An additional group of rats was treated with a higher dose of Ang II (750 µg/kg per d); these rats had renal and cardiac hydroxyproline content of 4.89±0.36 and 4.44±0.53 µg/mg dry tissue, respectively, not significantly different from the POPi and Ang II+POPi groups. This indicates that the maximum fibrotic effect may be achieved by POPi. Figure 2 shows representative images of PVF from heart and kidney sections stained with picrosirius red as well as the cumulative data. POPi alone significantly increased PVF. A low dose of Ang II increased PVF slightly but the difference was not significant, and the combined treatment increased perivascular collagen similarly to POPi alone, which was not significantly different from Ang II alone. Figure 3 shows interstitial cardiac fibrosis, and Figure 4 shows interstitial cell proliferation and number of prolyl 4-hydroxylase expressing cells. POPi or Ang II alone did not have any significant effect; however, the combined treatment significantly increased interstitial collagen deposition, cell proliferation, and prolyl 4-hydroxylase expressing cells compared with Ang II alone.
|
|
|
Effect of POPi on Mesangial Matrix Deposition in the Presence or Absence of Ang II
Paraffin-embedded kidney sections were stained using PAS, which is used to examine mesangial matrix deposition. Figure 5 shows representative images and cumulative data, expressed as per cent of glomerular area positively stained by PAS. POPi or Ang II alone significantly increased PAS staining compared with vehicle; however, the combined treatment had no additional effect.
|
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionReferences |
|---|
We have accumulated extensive evidence of the antifibrotic properties of Ac-SDKP when administered chronically in rat models of hypertension and myocardial infarction4,14,15; however, we questioned whether this peptide would have any physiological role at normal concentrations. In this study we found that chronic treatment with an oral POPi, which blocked the release of Ac-SDKP from its precursor thymosin-ß4,9 significantly decreased cardiac and renal endogenous levels of Ac-SDKP in normal rats and promoted collagen deposition, perivascular fibrosis, and glomerulosclerosis, suggesting that this peptide helps regulate normal collagen content.
Prolyl oligopeptidase (POP, EC 3.4.21.26), also called prolyl endopeptidase, is widely distributed in mammalian tissues and has been isolated from several organs (brain, kidney, liver, muscle) from various species (human, rat, rabbit, lamb, cow).16 POP is involved in the degradation of various neuropeptides,17 such as Arg8-vasopressin and substance-P, whose levels may rise during POPi treatment. Because Arg8-vasopressin and substance-P reportedly stimulate fibroblast proliferation in vitro,18–20 which could increase collagen deposition, we measured cardiac and renal levels of Arg8-vasopressin and substance-P. In a pilot study, we found that endogenous levels of these profibrotic neuropeptides were not affected by POPi in the heart and kidneys whereas they were slightly increased in the brain, in agreement with other studies11,21; however, this increase did not reach significance, possibly because of the fact that we homogenized the entire brain and the neuropeptides are reportedly significantly increased only in some regions of the brain (frontal cortex and hypothalamus) after treatment with S 17092.21,22 On the contrary, chronic POPi administration significantly decreased Ac-SDKP, suggesting that the increase in collagen deposition observed in rats treated with POPi is not likely caused by a possible increase in profibrotic neuropeptides but rather to decreased endogenous levels of Ac-SDKP. POP is also one of the enzymes (along with neutral endopeptidase 24.11, thimet oligopeptidase, prolyl carboxypeptidase23 and ACE224) involved in the degradation of Ang I and Ang II forming Ang 1-7. Although contribution to the conversion of Ang 1-7 by different enzymes was dependent on tissue and biochemical environment, current data reported by several investigators suggest that POP does not contribute significantly to the formation of Ang 1-7 in vivo.25–27
In this study, we used a low dose of Ang II, because we wanted to avoid maximal fibrotic effects. We found that collagen content and perivascular fibrosis were slightly increased in the rats given a low dose of Ang II, and the combination of Ang II and POPi had no further effect compared with POPi alone, suggesting that the maximum fibrotic effect may be reached with the POPi, as it was confirmed with a higher dose of Ang II.
The fact that decreasing normal endogenous levels of Ac-SDKP promoted excessive collagen deposition may indicate that this tetrapeptide plays a role in normal collagen turnover, either decreasing the rate of collagen synthesis or promoting its degradation. This hypothesis has been also suggested by Pokharel et al, who recently showed that enhanced breakdown of endogenous Ac-SDKP attributable to cardiac ACE overexpression (because Ac-SDKP is a natural ACE substrate28) is responsible for the increase in cardiac collagen.29 One interesting finding was that interstitial collagen fraction was not increased with POPi alone, in contrast to PVF; however, the combined treatment of POPi plus Ang II significantly increased interstitial collagen fraction compared with Ang II alone, and this was accompanied by an increase in interstitial cell proliferation and prolyl 4-hydroxylase-expressing cells. These observations may suggest that Ac-SDKP participates in maintenance of the collagen balance, so that a decrease in endogenous levels would affect remodeling of the myocardium similarly to hypertension, which occurs initially in the perivascular portion and progressively extends to cause widespread interstitial fibrosis; this process may be accelerated in the presence of a profibrotic stimulus, such as Ang II. Although the increase in interstitial collagen in the combined Ang II+POPi group is significant by itself, it does not represent a high percentage of total organ collagen content, which is derived mainly from the perivascular portion, perhaps explaining why no additive effect was seen when total collagen was assessed.
We previously showed that chronic administration of Ac-SDKP prevents interstitial collagen deposition in hypertension and myocardial infarction4,15 possibly by decreasing interstitial cell proliferation, monocyte/macrophage infiltration, and transforming growth factor (TGF)-ß expression7 as well as fibroblast proliferation.30 In the present study we found that interstitial cell number was increased in the rats given the combined treatment, and this corresponded to increased interstitial collagen in the heart. Although we could not identify the type of proliferating interstitial cells, it is possible that some would be fibroblasts, because the number of prolyl 4-hydroxylase-positive cells (a marker for fibroblasts31) likewise increased.
We also found that decreased endogenous levels of Ac-SDKP promoted glomerulosclerosis, suggesting that Ac-SDKP is involved in normal mesangial matrix turnover. This is supported by a recent report showing that chronic treatment with Ac-SDKP prevented kidney damage and reduced mesangial matrix expansion in diabetic mice.6
It is worth noting that the effects of POPi treatment on collagen deposition were not attributable to changes in blood pressure, because POPi did not increase systolic blood pressure as reported previously.9 The low dose of Ang II used in this study reduced basal plasma levels of Ac-SDKP. Although we do not currently have a good explanation for this observation, we do not believe it negates our observations or confounds our interpretation of the results, because tissue contents were not affected by Ang II treatment, which is the relevant parameter to consider when organ fibrosis is analyzed.
Limitations of Our Study
In vitro studies using the purified enzyme revealed that POP has many substrates, including substance-P, Arg8-vasopressin, and Ang I and II (POP action on Ang I and II results in formation of Ang 1-7).32 A wide range of Km values has been reported, depending on the species and tissues (see Welches et al33 for review). Although angiotensins reportedly have the lowest Km for POP, to conclude that they are the best substrates, possessing the highest affinity in vivo, would be an oversimplification. We designed a pilot study to evaluate the effects of S 17092 on levels of natural POP substrates; however, we were more concerned with the profibrotic neuropeptides substance-P and Arg8-vasopressin, because they were reportedly increased significantly by S17092 in some regions of the brain such as the hypothalamus and frontal cortex,11 and if the same is true in other organs, that may favors an increase in fibrosis.21
We are not aware of any available data showing the effects of chronic POPi treatment on angiotensin peptides. We only measured Ang II after 7 days (pilot study) and there was no change in organ levels with POPi. Because we observed a similar reduction in organ Ac-SDKP content after 7 and 60 days of POPi treatment (Tables 1 and 2
), we have no reason to believe that Ang II would be affected after 60 days.
|
Conclusion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionReferences |
|---|
We concluded that significant reduction of endogenous Ac-SDKP in the heart and kidneys promotes collagen deposition and perivascular fibrosis as well as glomerulosclerosis, suggesting that this peptide helps regulate collagen content under normal conditions. We believe this is the first study showing that Ac-SDKP has a physiological role at basal concentrations, preventing organ collagen accumulation.
Perspectives and Significance
In this study we found that Ac-SDKP plays an important physiological role in maintenance of the collagen balance, because decreasing endogenous levels of Ac-SDKP increased net collagen content. Extracellular matrix proteins exhibit continuous turnover, and we still do not know whether Ac-SDKP participates in slowing collagen synthesis, accelerating degradation, or both. However, we believe our findings contribute to knowledge of the mechanisms that regulate collagen accumulation and may help in selecting potential targets for treatment of fibrosis.
|
Acknowledgments |
|---|
Source of Funding
This work was supported by a National Institutes of Health grant K01 HL076581 (to M.A.C.).
Disclosures
None.
Received November 7, 2006; first decision November 24, 2006; accepted April 10, 2007.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionConclusionReferences |
|---|
- Pradelles P, Frobert Y, Créminon C, Liozon E, Massé A, Frindel E. Negative regulator of pluripotent hematopoietic stem cell proliferation in human white blood cells and plasma as analysed by enzyme immunoassay. Biochem Biophys Res Commun. 1990; 170: 986–993.[CrossRef][Medline] [Order article via Infotrieve]
- Pradelles P, Frobert Y, Créminon C, Ivonine H, Frindel E. Distribution of a negative regulator of haematopoietic stem cell proliferation (AcSDKP) and thymosin b4 in mouse tissues. FEBS Lett. 1991; 289: 171–175.[CrossRef][Medline] [Order article via Infotrieve]
- Peng H, Carretero OA, Brigstock DR, Oja-Tebbe N, Rhaleb N-E. Ac-SDKP reverses cardiac fibrosis in rats with renovascular hypertension. Hypertension. 2003; 42: 1164–1170.
[Abstract/Free Full Text] - Yang F, Yang X-P, Liu Y-H, Xu J, Cingolani O, Rhaleb N-E, Carretero OA. Ac-SDKP reverses inflammation and fibrosis in rats with heart failure after myocardial infarction. Hypertension. 2004; 43: 229–236.
[Abstract/Free Full Text] - Cingolani OH, Yang X-P, Liu Y-H, Villanueva M, Rhaleb N-E, Carretero OA. Reduction of cardiac fibrosis decreases systolic performance without affecting diastolic function in hypertensive rats. Hypertension. 2004; 43: 1067–1073.
[Abstract/Free Full Text] - Shibuya K, Kanasaki K, Isono M, Sato H, Omata M, Sugimoto T, Araki S, Isshiki K, Kashiwagi A, Haneda M, Koya D. N-acetyl-seryl-aspartyl-lysyl-proline prevents renal insufficiency and mesangial matrix expansion in diabetic db/db mice. Diabetes. 2005; 54: 838–845.
[Abstract/Free Full Text] - Peng H, Carretero OA, Vuljaj N, Liao T-D, Motivala A, Peterson EL, Rhaleb N-E. Angiotensin-converting enzyme inhibitors. A new mechanism of action. Circulation. 2005; 112: 2436–2445.
[Abstract/Free Full Text] - Polgár L. Prolyl oligopeptidases. Methods Enzymol. 1994; 244: 188–200.[CrossRef][Medline] [Order article via Infotrieve]
- Cavasin MA, Rhaleb N-E, Yang X-P, Carretero OA. Prolyl oligopeptidase is involved in release of the antifibrotic peptide Ac-SDKP. Hypertension. 2004; 43: 1140–1145.
[Abstract/Free Full Text] - Barelli H, Petit A, Hirsch E, Wilk S, De Nanteuil G, Morain P, Checler F. S 17092-1, a highly potent, specific and cell permeant inhibitor of human proline endopeptidase. Biochem Biophys Res Commun. 1999; 257: 657–661.[CrossRef][Medline] [Order article via Infotrieve]
- Morain P, Lestage P, De Nanteuil G, Jochemsen R, Robin J-L, Guez D, Boyer P-A. S 17092: a prolyl endopeptidase inhibitor as a potential therapeutic drug for memory impairment. Preclinical and clinical studies. CNS Drug Rev. 2002; 8: 31–52.[Medline] [Order article via Infotrieve]
- Woessner JF Jr. The determination of hydroxyproline in tissue and protein samples containing small proportions of this imino acid. Arch Biochem Biophys. 1961; 93: 440–447.[CrossRef][Medline] [Order article via Infotrieve]
- Hochberg Y. A Sharper Bonferroni procedure for multiples tests of significance. Biometrika. 1988; 75: 800–802.
[Abstract/Free Full Text] - Rasoul S, Carretero OA, Peng H, Cavasin MA, Zhuo J, Sanchez-Mendoza A, Brigstock DR, Rhaleb N-E. Antifibrotic effect of Ac-SDKP and angiotensin-converting enzyme inhibition in hypertension. J Hypertens. 2004; 22: 593–603.[CrossRef][Medline] [Order article via Infotrieve]
- Peng H, Carretero OA, Raij L, Yang F, Kapke A, Rhaleb N-E. Antifibrotic effects of N-acetyl-seryl-aspartyl-lysyl-proline on the heart and kidney in aldosterone-salt hypertensive rats. Hypertension. 2001; 37: 794–800.
[Abstract/Free Full Text] - Wilk S. Prolyl endopeptidase. Life Sci. 1983; 33: 2149–2157.[CrossRef][Medline] [Order article via Infotrieve]
- Checler F. Neuropeptide-degrading peptidase. In: Parvez SH, Naoi M, Nagatsu T, Parvez S. eds. Methods in Neurotransmitters and Neuropeptides, Part 2. Amsterdam: Elsevier Science Publishers; 1993: 375–418.
- Yang XD, Zhao LY, Zheng QS, Li X. Effects of arginine vasopressin on growth of rat cardiac fibroblasts: role of V1 receptor. J Cardiovasc Pharmacol. 2003; 42: 132–135.[CrossRef][Medline] [Order article via Infotrieve]
- Kumaran C, Shivakumar K. Calcium- and superoxide anion-mediated mitogenic action of substance P on cardiac fibroblasts. Am J Physiol Heart Circ Physiol. 2002; 282: H1855–H1862.
[Abstract/Free Full Text] - Burssens P, Steyaert A, Forsyth R, van Ovost EJ, De Paepe Y, Verdonk R. Exogenously administered substance P and neutral endopeptidase inhibitors stimulate fibroblast proliferation, angiogenesis and collagen organization during Achilles tendon healing. Foot Ankle Int. 2005; 26: 832–839.[Medline] [Order article via Infotrieve]
- Bellemère G, Vaudry H, Morain P, Jégou S. Effect of prolyl endopeptidase inhibition on arginine-vasopressin and thyrotrophin-releasing hormone catabolism in the rat brain. J Neuroendocrinol. 2005; 17: 306–313.[CrossRef][Medline] [Order article via Infotrieve]
- Bellemere G, Morain P, Vaudry H, Jegou S. Effect of S 17092, a novel prolyl endopeptidase inhibitor, on substance P and alpha-melanocyte-stimulating hormone breakdown in the rat brain. J Neurochem. 2003; 84: 919–929.[CrossRef][Medline] [Order article via Infotrieve]
- Santos RA, Campagnole-Santos MJ, Andrade SP. Angiotensin-(1-7): an update. Regul Pept. 2000; 91: 45–62.[CrossRef][Medline] [Order article via Infotrieve]
- Donoghue M, Hsieh F, Baronas E, Godbout K, Gosselin M, Stagliano N, Donovan M, Woolf B, Robison K, Jeyaseelan R, Breitbart RE, Acton S. A novel angiotensin-converting enzyme-related carboxypeptidase (ACE2) converts angiotensin I to angiotensin 1–9. Circ Res. 2000; 87: e1–e9.[Medline] [Order article via Infotrieve]
- Yamamoto K, Chappell MC, Brosnihan KB, Ferrario CM. In vivo metabolism of angiotensin I by neutral endopeptidase (EC 3.4.24.11) in spontaneously hypertensive rats. Hypertension. 1992; 19: 692–696.
[Abstract/Free Full Text] - Chappell MC, Gomez MN, Pirro NT, Ferrario CM. Release of angiotensin-(1-7) from the rat hindlimb. Influence of angiotensin-converting enzyme inhibition. Hypertension. 2000; 35: 348–352.
[Abstract/Free Full Text] - Carey RM, Siragy HM. Newly recognized components of the renin-angiotensin system: potential roles in cardiovascular and renal regulation. Endocr Rev. 2003; 24: 261–271.
[Abstract/Free Full Text] - Azizi M, Ezan E, Nicolet L, Grognet JM, Menard J. High plasma level of N-acetyl-seryl-aspartyl-lysyl-proline: a new marker of chronic angiotensin-converting enzyme inhibition. Hypertension. 1997; 30: 1015–1019.
[Abstract/Free Full Text] - Pokharel S, van Geel PP, Sharma UC, Cleutjens JPM, Bohnemeier H, Tian X-L, Schunkert H, Crijns HJGM, Paul M, Pinto YM. Increased myocardial collagen content in transgenic rats overexpressing cardiac angiotensin-converting enzyme is related to enhanced breakdown of N-acetyl-Ser-Asp-Lys-Pro and increased phosphorylation of Smad2/3. Circulation. 2004; 110: 3129–3135.
[Abstract/Free Full Text] - Rhaleb N-E, Peng H, Harding P, Tayeh M, LaPointe MC, Carretero OA. Effect of N-acetyl-seryl-aspartyl-lysyl-proline on DNA and collagen synthesis in rat cardiac fibroblasts. Hypertension. 2001; 37: 827–832.
[Abstract/Free Full Text] - Ishikawa Y, Akasaka Y, Ishii T, Yoda-Murakami M, Choi-Miura NH, Tomita M, Ito K, Zhang L, Akishima Y, Ishihara M, Muramatsu M, Taniyama M. Changes in the distribution pattern of gelatin-binding protein of 28 kDa (adiponectin) in myocardial remodelling after ischaemic injury. Histopathology. 2003; 42: 43–52.[CrossRef][Medline] [Order article via Infotrieve]
- Moriyama A, Nakanishi M, Sasaki M. Porcine muscle prolyl endopeptidase and its endogenous substrates. J Biochem (Tokyo). 1988; 104: 112–117.
[Abstract/Free Full Text] - Welches WR, Brosnihan KB, Ferrario CM. A comparison of the properties and enzymatic activities of three angiotensin processing enzymes: angiotensin converting enzyme, prolyl endopeptidase and neutral endopeptidase 24.11. Life Sci. 1993; 52: 1461–1480.[CrossRef][Medline] [Order article via Infotrieve]
This article has been cited by other articles:
 |
|
 |
|
  C.-X. Lin, N.-E. Rhaleb, X.-P. Yang, T.-D. Liao, M. A. D'Ambrosio, and O. A. Carretero Prevention of aortic fibrosis by N-acetyl-seryl-aspartyl-lysyl-proline in angiotensin II-induced hypertension Am J Physiol Heart Circ Physiol, September 1, 2008; 295(3): H1253 - H1261. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
U. Sharma, N.-E. Rhaleb, S. Pokharel, P. Harding, S. Rasoul, H. Peng, and O. A. Carretero Novel anti-inflammatory mechanisms of N-Acetyl-Ser-Asp-Lys-Pro in hypertension-induced target organ damage Am J Physiol Heart Circ Physiol, March 1, 2008; 294(3): H1226 - H1232. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||