Biomedical subjects

Adviye Ergul

Publications and source records attributed to Adviye Ergul.

At least 19 recordsLinked to original sources

PubMed2006

Delayed minocycline inhibits ischemia-activated matrix metalloproteinases 2 and 9 after experimental stroke.

BACKGROUND: Matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) are increased in the brain after experimental ischemic stroke in rats. These two proteases are involved with the degradation of the basal lamina and loss of stability of the blood brain barrier that occurs after ischemia and that is associated with thrombolytic therapy in ischemic stroke. Minocycline is a lipophilic tetracycline and is neuroprotective in several models of brain injury. Minocycline inhibits inflammation, apoptosis and extracellular matrix degradation. In this study we investigated whether delayed minocycline inhibits brain MMPs activated by ischemia in a model of temporary occlusion in Wistar rats. RESULTS: Both MMP-2 and MMP-9 were elevated in the ischemic tissue as compared to the contra-lateral hemisphere after 3 hours occlusion and 21 hours survival (p < 0.0001 for MMP-9). Intraperitoneal minocycline at 45 mg/kg concentration twice a day (first dose immediately after the onset of reperfusion) significantly reduced gelatinolytic activity of ischemia-elevated MMP-2 and MMP-9 (p < 0.0003). Treatment also reduced protein concentration of both enzymes (p < 0.038 for MMP-9 and p < 0.018 for MMP-2). In vitro incubation of minocycline in concentrations as low as 0.1 mug/ml with recombinant MMP-2 and MMP-9 impaired enzymatic activity and MMP-9 was more sensitive at lower minocycline concentrations (p < 0.05). CONCLUSION: Minocycline inhibits enzymatic activity of gelatin proteases activated by ischemia after experimental stroke and is likely to be selective for MMP-9 at low doses. Minocycline is a potential new therapeutic agent to acute treatment of ischemic stroke.

Animals↗

PubMed2006

Type-2 diabetes-induced changes in vascular extracellular matrix gene expression: relation to vessel size.

BACKGROUND: Hyperglycemia-induced changes in vascular wall structure contribute to the pathogenesis of diabetic microvascular and macrovascular complications. Matrix metalloproteinases (MMP), a family of proteolytic enzymes that degrade extracellular matrix (ECM) proteins, are essential for vascular remodeling. We have shown that endothelin-1 (ET-1) mediates increased MMP activity and associated vascular remodeling in Type 2 diabetes. However, the effect of Type 2 diabetes and/or ET-1 on the regulation of ECM and MMP gene expression in different vascular beds remains unknown. METHODS: Aorta and mesenteric artery samples were isolated from control, Type 2 diabetic Goto-Kakizaki (GK) rats and GK rats treated with ETA antagonist ABT-627. Gene expression profile of MMP-2, MMP-9, MT1-MMP, fibronectin, procollagen type 1, c-fos and c-jun, were determined by quantitative real-time (qRT) PCR. In addition, aortic gene expression profile was evaluated by an ECM & Adhesion Molecules pathway specific microarray approach. RESULTS: Analysis of the qRT-PCR data demonstrated a significant increase in mRNA levels of MMPs and ECM proteins as compared to control animals after 6 weeks of mild diabetes. Furthermore, these changes were comparable in aorta and mesentery samples. In contrast, treatment with ETA antagonist prevented diabetes-induced changes in expression of MMPs and procollagen type 1 in mesenteric arteries but not in aorta. Microarray analysis provided evidence that 27 extracellular matrix genes were differentially regulated in diabetes. Further qRT-PCR with selected 7 genes confirmed the microarray data. CONCLUSION: These results suggest that the expression of both matrix scaffold protein and matrix degrading MMP genes are altered in macro and microvascular beds in Type 2 diabetes. ETA antagonism restores the changes in gene expression in the mesenteric bed but not in aorta suggesting that ET-1 differentially regulates microvascular gene expression in Type 2 diabetes.

Animals↗

PubMed2006

Hypertension after experimental cerebral ischemia: candesartan provides neurovascular protection.

BACKGROUND: After ischemic stroke, hypertension increases the risk of recurrence, hemorrhage and fatal cerebral edema, but blood pressure (BP) lowering in the acute stroke period is controversial due to fears of infarct extension and worsened outcomes. OBJECTIVE: To determine whether BP lowering with candesartan, initiated at reperfusion, can reduce neurovascular damage and improve outcome in a model of hypertension after experimental ischemic stroke. METHODS: Male Wistar rats (280-305 g) underwent 3 h of middle cerebral artery occlusion (MCAO). At reperfusion, either saline (n = 18) or candesartan 1 mg/kg (n = 18) was administered intravenously. BP was measured by telemetry for 2 days before and 24 h after MCAO. Neurologic function was assessed and sacrifice occurred at 24 h after occlusion. Brain tissue was analyzed for infarct size, hemoglobin content and edema. RESULTS: Mean BP increased from 96 to 124 mmHg immediately upon MCAO and decreased to 114 mmHg after reperfusion, remaining elevated for 24 h (P < 0.001) in the saline group. Candesartan reduced BP back to baseline and BP remained lower than in saline-treated animals until sacrifice (P < 0.001). Infarct size (54 versus 38%, P = 0.01) and hemoglobin content (23.4 versus 10.0 microg/g tissue; P = 0.03) and edema (17.97 versus 11.33%, P < 0.0001) were lower in the candesartan group. In addition, neurologic function at 24 h was improved (P = 0.0036) in the candesartan group. CONCLUSIONS: Candesartan administered after reperfusion in acute ischemic stroke reduces neurovascular damage and improves outcome.

Animals↗

PubMed2006

Elevated endothelin-1 levels are associated with decreased arterial elasticity in hypertensive patients.

Endothelin-1 stimulates collagen synthesis and is increased in hypertension, but its effect on collagen degradation remains unknown. The current study tested the hypothesis that elevated endothelin-1 levels are associated with decreased collagenase activity, markers of collagen degradation, and arterial compliance in hypertensive patients. Normotensive (n = 10) and hypertensive (n = 13) patients who were not on any antihypertensive medication were recruited, and small and large artery elasticity index, systemic vascular resistance, pulse pressure, and blood pressure were determined using blood pressure waveform analysis. Large artery elasticity index and collagen degradation products were decreased whereas endothelin-1, systemic vascular resistance, and pulse pressure were elevated in hypertensive patients. Plasma endothelin-1 was negatively correlated with a cross-linked C-terminal telopeptide of collagen type I, a collagen degradation marker (r = -0.43; p = 0.04), collagenase matrix metalloproteinase-1 (r = -0.48; p = 0.02), and large artery elasticity (r = -0.45; p = 0.03) and positively correlated with pulse pressure (r = 0.68; p = 0.0005). These results suggest that endothelin-1 contributes to decreased arterial compliance in hypertension via inhibition of collagen degradation.

Adult↗

PubMed2006

Phosphorylation of endothelin converting enzyme-1 isoforms: relevance to subcellular localization.

Endothelin-converting enzyme (ECE)-1 is a metalloenzyme with four subisoforms, which differ only in their amino-terminal domain. ECE-1a and c are the most common isoforms and are found at the plasma membrane and in the Golgi complex, whereas ECE-1b displays lysosomal localization. We have recently shown that ECE-1a but not ECE-1b also colocalizes with nuclear membrane markers, and that maintenance of cells in high glucose (25 mM) promotes relocalization of ECE-1a from the membrane to the intracellular compartment. To investigate the mechanisms involved in this process, we conducted a search for potential phosphorylation sites, which yielded a different number of putative sites for protein kinase (PK)-C and PKA in the amino-terminal region. Stimulation of Chinese hamster ovary (CHO) cells expressing a green fluorescent protein (GFP)-tagged human ECE-1a or ECE-1b with 100 nM phorbol myristate acetate (PMA) resulted in phosphorylation of ECE-1a, as determined by immunoprecipitation with an antibody to GFP followed by immunoblotting with an antibody to phosphoserine. Stimulation of cells with PMA also promoted intracellular relocalization, as seen in cells grown under high-glucose conditions. Incubation of cells grown in 25 mM glucose with the PKC inhibitor, calphostin C (100 nM), partially prevented the relocalization of ECE-1a from the plasma membrane to intracellular compartments. Stimulation of cells with 100 nM forskolin caused phosphorylation of ECE-1b and not ECE-1a, which is consistent with the lack of a putative PKA site in the ECE-1a amino-terminal sequence. Although phosphorylation is not required for ECE-1 enzymatic activity, these results suggest that ECE-1 isoforms are phosphorylated and that phosphorylation might play an important role in the regulation of intracellular trafficking of ECE-1 subisoforms.

Animals↗

PubMed2006

Microvascular versus macrovascular dysfunction in type 2 diabetes: differences in contractile responses to endothelin-1.

Vascular dysfunction characterized by a hyperreactivity to vasoconstrictors and/or impaired vascular relaxation contributes to increased incidence of cardiovascular disease in diabetes. Endothelin (ET)-1, a potent vasoconstrictor, is chronically elevated in diabetes. However, the role of ET-1 in resistance versus larger vessel function in mild diabetes remains unknown. Accordingly, this study investigated vascular function of third-order mesenteric arteries and basilar arteries in control Wistar and Goto-Kakizaki (GK) rats, a model of mild Type 2 diabetes. Six weeks after the onset of diabetes, contractile responses to 0.1-100 nM ET-1 and relaxation responses to 1 nM-10 microM acetylcholine (ACh) in vessels preconstricted (baseline + 60%) with serotonin (5-HT) were assessed by myograph studies in the presence or absence of a nitric oxide synthase (NOS) inhibitor, N-nitro-L-arginine (L-NNA). Maximum contractile response to ET-1 was augmented in mesenteric vessels (155 +/- 18% in GK vs. 81 +/- 6% in control; n = 5-7) but not in the basilar artery (134 +/- 29% in GK vs. 107 +/- 17% in control; n = 4 per group). However, vascular relaxation was impaired in the basilar arteries (22 +/- 4% in GK vs. 53 +/- 7% in control; n = 4 per group) but not in mesenteric arteries of GK rats. Inhibition of NOS decreased the relaxation response of basilar arteries to 15 +/- 8% and 42 +/- 5% in GK and control rats, respectively; whereas, in resistance vessels, corresponding values were 56 +/- 7% and 89 +/- 3% (vs. 109 +/- 2% and 112 +/- 3% without NOS blockade), indicating the involvement of different vasorelaxation-promoting pathways in these vascular beds. These findings provide evidence that the ET system is activated even under mild hyperglycemia and that it contributes to the hyperreactivity of resistance vessels, therefore, the ET system may play an important role in elevated blood pressure in Type 2 diabetes.

Acetylcholine↗

PubMed2005

Endothelin antagonism prevents early EGFR transactivation but not increased matrix metalloproteinase activity in diabetes.

Although past studies have demonstrated decreased renal matrix metalloproteinase (MMP) activity in type 1 diabetes and in mesangial cells grown under high glucose conditions, renal MMP expression and activity in type 2 diabetes and the regulation of MMPs by profibrotic factors involved in diabetic renal complications such as endothelin-1 (ET-1) remained unknown. The renal expression and activity of MMPs in type 2 diabetic Goto-Kakizaki (GK) rats treated with vehicle or ET(A) receptor selective antagonist ABT-627 for 4 wk were assessed by gelatin zymography, fluorogenic gelatinase assay, and immunoblotting. In addition, expression and phosphorylation of epidermal growth factor receptor (EGFR) and connective tissue growth factor were evaluated by immunoblotting. Renal sections stained with Masson trichrome were used to investigate kidney structure. MMP-2 activity and protein levels were significantly increased in both cortical and medullary regions in the GK rats. Membrane-bound MMP (MT1-MMP), MMP-9, and fibronectin levels were also increased, and ABT-627 treatment did not have an effect on MMP activity and expression. Histological analysis of kidneys did not reveal any structural changes. Phosphorylation of EGFR was significantly increased in the diabetic animals, and ABT-627 treatment prevented this increase, suggesting ET-1-mediated transactivation of EGFR. These results suggest that there is early upregulation of renal MMPs in the absence of any kidney damage. Although the ET(A) receptor subtype is not involved in the early activation of MMPs in type 2 diabetes, ET-1 contributes to transactivation of growth-promoting and profibrotic EGFR.

Animals↗

PubMed2005

Effect of neutrophil depletion on gelatinase expression, edema formation and hemorrhagic transformation after focal ischemic stroke.

BACKGROUND: While gelatinase (MMP-2 and -9) activity is increased after focal ischemia/reperfusion injury in the brain, the relative contribution of neutrophils to the MMP activity and to the development of hemorrhagic transformation remains unknown. RESULTS: Anti-PMN treatment caused successful depletion of neutrophils in treated animals. There was no difference in either infarct volume or hemorrhage between control and PMN depleted animals. While there were significant increases in gelatinase (MMP-2 and MMP-9) expression and activity and edema formation associated with ischemia, neutrophil depletion failed to cause any change. CONCLUSION: The main finding of this study is that, in the absence of circulating neutrophils, MMP-2 and MMP-9 expression and activity are still up-regulated following focal cerebral ischemia. Additionally, neutrophil depletion had no influence on indicators of ischemic brain damage including edema, hemorrhage, and infarct size. These findings indicate that, at least acutely, neutrophils are not a significant contributor of gelatinase activity associated with acute neurovascular damage after stroke.

Animals↗

PubMed2005

Oxidative stress and the use of antioxidants in diabetes: linking basic science to clinical practice.

Cardiovascular complications, characterized by endothelial dysfunction and accelerated atherosclerosis, are the leading cause of morbidity and mortality associated with diabetes. There is growing evidence that excess generation of highly reactive free radicals, largely due to hyperglycemia, causes oxidative stress, which further exacerbates the development and progression of diabetes and its complications. Overproduction and/or insufficient removal of these free radicals result in vascular dysfunction, damage to cellular proteins, membrane lipids and nucleic acids. Despite overwhelming evidence on the damaging consequences of oxidative stress and its role in experimental diabetes, large scale clinical trials with classic antioxidants failed to demonstrate any benefit for diabetic patients. As our understanding of the mechanisms of free radical generation evolves, it is becoming clear that rather than merely scavenging reactive radicals, a more comprehensive approach aimed at preventing the generation of these reactive species as well as scavenging may prove more beneficial. Therefore, new strategies with classic as well as new antioxidants should be implemented in the treatment of diabetes.

Animals↗

PubMed2005

Oxidative stress and cardiovascular disease: antioxidants and unresolved issues.

Experimental and clinical studies suggest that oxidative stress contributes to the development and progression of cardiovascular disease. However, clinical trials with classic vitamin antioxidants failed to demonstrate any benefit in cardiovascular outcomes. Recent advances in our understanding of mechanisms involved in free radical generation reinstate that a more comprehensive approach targeting the prevention of reactive oxygen species (ROS) formation early in the disease process may prove beneficial. Experimental studies and reviews in oxidative stress were selected to provide a better understanding of the roles of the reactive species in the initiation and progression of cardiovascular disease (CVD). Clinical studies that evaluated the efficacy of several classes of antioxidants in CVD were included in the second part of this review to discuss future therapeutic guidelines based on currently available evidence. In conclusion, before a potential role for antioxidants in the treatment of CVD is eliminated, more carefully designed studies with classic as well as new antioxidants in well-defined patient populations are warranted to provide a definitive answer.

Animals↗

PubMed2005

Tactics for vascular protection after acute ischemic stroke.

BACKGROUND: The vascular events that happen during ischemic stroke worsen outcomes in patients by causing edema, hemorrhagic transformation, and general neurologic tissue compromise. In the past 2 decades, clinical trials in patients after ischemic stroke focused on neuroprotection, but these strategies have failed in providing actual benefit. Vascular protection represents a new field to be explored in acute ischemic stroke in order to develop new approaches to therapeutic intervention. PURPOSE: We identified tactics likely to provide vascular protection in patients with ischemic stroke. These tactics are based on knowledge of the molecular processes involved. SUMMARY OF REVIEW: The pathologic processes due to vascular injury after an occlusion of a cerebral artery can be separated into acute (those occurring within hrs), subacute (hrs to days), and chronic (days to mo). Targets for intervention can be identified for all three stages. In the acute phase, superoxide is the predominant mediator, followed by inflammatory mediators and proteases in the subacute phase. In the chronic phase, proapoptotic gene products have been implicated. Many already-marketed therapeutic agents (statins, angiotensin modulators, erythropoietin, minocycline, and thiazolidinediones), with proven safety in patients, have been shown to have activity against some of the key targets of vascular protection. CONCLUSION: Currently available pharmacologic agents are poised for clinical trials of vascular protection after acute ischemic stroke.

Acute Disease↗

PubMed2005

Type 2 diabetes causes remodeling of cerebrovasculature via differential regulation of matrix metalloproteinases and collagen synthesis: role of endothelin-1.

The risk of cerebrovascular disease is four- to sixfold higher in patients with diabetes. Vascular remodeling, characterized by extracellular matrix deposition and an increased media-to-lumen ratio, occurs in diabetes and contributes to the development of complications. However, diabetes-induced changes in the cerebrovascular structure remain unknown. Endothelin-1 (ET-1), a potent vasoconstrictor with profibrotic properties, is chronically elevated in diabetes. To determine diabetes-mediated changes in the cerebrovasculature and the role of ET-1 in this process, type 2 diabetic Goto-Kakizaki (GK) rats were administered an ET(A) receptor antagonist for 4 weeks. Middle cerebral arteries were harvested and studies were performed to determine vascular structure. Tissue and plasma ET-1 levels were increased in GK rats compared with controls. Significant medial hypertrophy and collagen deposition resulted in an increased wall-to-lumen ratio in diabetic rats that was reduced by ET(A) receptor antagonism. Vascular matrix metalloproteinase (MMP)-2 activity was higher, but MMP-1 levels were significantly reduced in GK rats, and MMP levels were restored to control levels by ET(A) receptor antagonism. We conclude that ET-1 promotes cerebrovascular remodeling in type 2 diabetes through differential regulation of MMPs. Augmented cerebrovascular remodeling may contribute to an increased risk of stroke in diabetes, and ET(A) receptor antagonism may offer a novel therapeutic target.

Animals↗

PubMed2004

Vascular dysfunction of venous bypass conduits is mediated by reactive oxygen species in diabetes: role of endothelin-1.

Diabetes is associated with increased risk for complications following coronary bypass grafting (CABG) surgery. Augmented superoxide (*O2*) production plays an important role in diabetic complications by causing vascular dysfunction. The potent vasoconstrictor endothelin-1 (ET-1) is also elevated in diabetes and following CABG; however, the effect of ET-1 on *O2* generation and/or vascular dysfunction in bypass conduits remain unknown. Accordingly, this study investigated basal and ET-1-stimulated *O2* production in bypass conduits and determined the effect of *O2* on conduit reactivity. Saphenous vein specimens were obtained from nondiabetic (n = 24) and diabetic (n = 24) patients undergoing CABG. Dihydroethidium staining and NAD(P)H oxidase activity assays (5380 +/- 940 versus 16,362 +/- 2550 relative light units/microg) demonstrated increased basal *O2* levels in the diabetes group (p < 0.05). Plasma ET-1 levels were associated with elevated basal *O2* levels, and treatment of conduits with exogenous ET-1 further increased *O2* production and augmented vasoconstriction. Furthermore, vascular relaxation was impaired in the diabetic group (75 versus 40%), which was restored by *O2* scavenger superoxide dismutase. These findings suggest that ET-1 causes bypass conduits dysfunction via stimulation of *O2* production in diabetes. Novel therapies that attenuate *O2* generation in bypass conduits may improve acute and late outcome of CABG in diabetic patients.

Blotting, Western↗

PubMed2004

Targets for vascular protection after acute ischemic stroke.

BACKGROUND: Vascular damage caused by cerebral ischemia leads to edema, hemorrhage formation, and worsened outcomes in ischemic stroke patients. Therapeutic interventions need to be developed to provide vascular protection. The purpose of this review is to identify the pathophysiologic processes involved in vascular damage after ischemia, which may lead to strategies to provide vascular protection in ischemic stroke patients. SUMMARY OF COMMENT: The pathologic processes caused by vascular injury after an occlusion of a cerebral artery can be separated into acute (hours), subacute (hours to days), and chronic (days to months). Targets for intervention can be identified for all 3 stages. Acutely, superoxide is the predominant mediator, followed by inflammatory mediators and proteases subacutely. In the chronic phase, proapoptotic gene products have been implicated. CONCLUSIONS: Pharmacological agents designed to target specific pathologic and protective processes affecting the vasculature should be used in clinical trials of vascular protection after acute ischemic stroke.

Acute Disease↗

PubMed2004

Vasoactive factors in sickle cell disease: in vitro evidence for endothelin-1-mediated vasoconstriction.

While systemic plasma endothelin-1 (ET-1) levels are increased during acute crisis in sickle cell disease, the relative levels of potent vasoactive factors that contribute to the regulation of vascular function, such as ET-1, NO, and cell-free hemoglobin, during the course of periodic vaso-occlusive episodes remain unclear. Moreover, whether and to what extent sickling-induced release of ET-1 alters vascular tone is not completely understood. To investigate the sequential changes in circulating vasoactive factors, we measured plasma ET-1, NO metabolites (NOx), and cell-free hemoglobin (Hb) before (steady-state), during (crisis), and after a vaso-occlusive (post-crisis) episode. Steady-state ET-1 levels (fmol/mL) increased from 2.3 +/- 0.4 to 11.0 +/- 1.4 and 4.2 +/- 1.0 during crisis and post-crisis periods, respectively. There was no significant difference in plasma NOx levels. Cell-free Hb levels were significantly higher in sickle cell patients in all phases as compared to the control group, and especially during crisis cell-free Hb levels were elevated by 4-fold (209,000 +/- 31,000 vs. 46,000 +/- 5,300 ng/mL in steady-state). Conditioned medium from human pulmonary artery endothelial cells exposed to sickled erythrocytes prepared by deoxygenation induced contraction of aortic rings, and this effect was blocked by an ET(A) receptor antagonist. These findings indicate that ET-1 is the predominant contractile factor released by cultured endothelial cells upon exposure to deoxygenated sickled SS erythrocytes and ET-1-NO-NO scavenger balance is altered in favor of vasoconstriction during an acute episode in SCD.

Anemia, Sickle Cell↗

PubMed2004

Downregulation of vascular matrix metalloproteinase inducer and activator proteins in hypertensive patients.

BACKGROUND: Peripheral vasculature undergoes extensive vascular remodeling in the hypertensive state. Regulation of extracellular matrix turnover by the matrix metalloproteinase (MMP) system is an important step in the vascular remodeling process. However, the expression pattern of the vascular MMP system in human hypertension remained unknown. METHODS AND RESULTS: Internal mammary artery specimens were obtained from normotensive (n = 13) and hypertensive (n = 19) patients undergoing coronary artery bypass grafting surgery. Zymographic analysis indicated a threefold decrease in total gelatinolytic activity of MMP-2 and MMP-9 in hypertension. MMP-1 activity was also decreased by fourfold without a significant change in protein levels. Tissue levels of extracellular matrix inducer protein (EMMPRIN), MMP activator protein (MT1-MMP), MMP-1, MMP-2, and MMP-9, as well as tissue inhibitors of MMPs (TIMP-1 and TIMP-2) were assessed by immunoblotting and yielded a significant decrease in MMP-9, EMMPRIN, and MT1-MMP levels in hypertension. In addition, measurement of plasma markers of collagen synthesis (procollagen type I amino-terminal propeptide [PINP]) and collagen degradation (carboxy-terminal telopeptide of collagen type I [ICTP]) indicated no difference in PINP levels but suppressed degradation of collagen in hypertension. Evaluation of profibrotic growth factors demonstrated higher levels of fibroblast growth factor (FGF)-2 in tissue preparations from hypertensive patients but no difference in transforming growth factor-beta1 levels. CONCLUSIONS: These findings demonstrate that not only MMP-1 and MMP-9, but MMP inducer and activator proteins are also downregulated in the hypertensive state. Augmented FGF-2 levels may contribute to parallel decreases in MMP activity and MMP induction system resulting in enhanced collagen deposition in hypertension.

Antigens, CD↗

PubMed2004

Sepiapterin decreases vasorelaxation in nitric oxide synthase inhibition-induced hypertension.

Exogenous BH4 (tetrahydrobiopterin) has been shown to improve endothelial function in cardiovascular disease; however, in the presence of elevated superoxide levels and decreased nitric oxide synthase (NOS) activity, BH4 may become autoxidized, resulting in reduced vasodilation. The authors tested the hypothesis that increasing BH4 will further reduce endothelium-dependent relaxation in aortas from rats made hypertensive by NOS inhibition. N omega-nitro-L-arginine (L-NNA, approximately 49 mg/kg/d) was administered in the rats' drinking water for 4 days. Systolic blood pressures, measured by tail-cuff technique, were significantly increased in L-NNA-treated rats. Endothelium-intact aortic segments were isolated and hung in organ chambers for the measurement of isometric force generation. Aortas from L-NNA-treated rats had decreased relaxation to acetylcholine compared with controls, and this was further decreased after incubation with sepiapterin. Superoxide dismutase (SOD) restored relaxation in aortas from L-NNA-treated rats to that of control. In addition, SOD or ascorbic acid reversed the sepiapterin-induced decrease in relaxation in aortas from L-NNA treated rats. Aortas from L-NNA-treated rats in the absence and presence of sepiapterin, and sepiapterin-treated control aortas, had increased dihydroethidium staining for superoxide compared with untreated controls. These results support the hypothesis that sepiapterin further reduces vasodilation in the presence of NOS inhibition and may be caused by BH4 autoxidation.

Animals↗

PubMed2004

Native matrix metalloproteinase characteristics may influence early stenosis of venous versus arterial coronary artery bypass grafting conduits.

PURPOSE: Stenosis and occlusion rates of internal mammary artery (IMA) and saphenous vein (SV) coronary artery bypass grafts (CABGs) are markedly different, which result from respective disparities in vascular remodeling. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) regulate vascular structure and may have important influence on graft patency. However, the MMP milieu and expression profile of the IMA and SV have not been contrasted. Therefore, the aim of this study was to assess and compare the native MMP systems in IMA vs SV conduits. METHODS: IMA (n = 10) and SV (n = 10) specimens were obtained from patients undergoing CABG surgery. Protein levels of MMP-1, MMP-2, and MMP-9, TIMP-1, a membrane-bound MMP activator (MT1-MMP), and an extracellular MMP inducer protein (EMMPRIN) were determined by immunoblotting and quantified by densitometric analysis. MMP-2 and MMP-9 activity was determined by gelatin zymography. RESULTS: MMP-2 levels were significantly higher in SV (2,218 +/- 351 pixels) vs IMA (1,012 +/- 213 pixels) specimens (mean +/- SEM]). There were no significant differences in MMP-1, MMP-9, or TIMP-1 content; however, MT1-MMP and EMMPRIN levels were significantly lower in SV (847 +/- 190 pixels, 1,742 +/- 461 pixels) vs IMA conduits (2,590 + 403 pixels, 5,606 + 678 pixels), respectively (p < 0.05). MMP-9 activity was similar while MMP-2 activity was significantly increased in SV vs IMA specimens. CONCLUSIONS: SV and IMA conduits harbor the same MMP molecular constituents. However, MMP-2 levels and activity are significantly more abundant in the SV compared to the IMA. These differences may contribute to the early pathologic remodeling of the SV vs IMA conduit following CABG surgery.

Aged↗