-
[show abstract]
[hide abstract]
ABSTRACT: The role of inflammation in the pathogenesis of abdominal aortic aneurysms (AAA) is well established. The inflammatory process leads to protease-mediated degradation of the extracellular matrix and apoptosis of smooth muscle cells (SMC), which are the predominant matrix synthesizing cells of the vascular wall. These processes act in concert to progressively weaken the aortic wall, resulting in dilatation and aneurysm formation. Oxidative stress is invariably increased in, and contributes importantly to, the pathophysiology of inflammation. Moreover, reactive oxygen species (ROS) play a key role in regulation of matrix metalloproteinases and induction of SMC apoptosis. ROS may also contribute to the pathogenesis of hypertension, a risk factor for AAA. Emerging evidence suggests that ROS and reactive nitrogen species (RNS) are associated with AAA formation in animal models and in humans. Although experimental data are limited, several studies suggest that modulation of ROS production or activity may suppress AAA formation and improve experimental outcome in rodent models. Although a number of enzymes can produce injurious ROS in the vasculature, increasing evidence points toward a role for NADPH oxidase as a source of oxidative stress in the pathogenesis of AAA.
Arteriosclerosis Thrombosis and Vascular Biology 04/2007; 27(3):461-9. · 6.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: 20-Hydroxyeicosatetraenoic acid (20-HETE), an arachidonic acid (AA) metabolite synthesized by cytochrome P-450 omega-oxidases, is reported to produce vasoconstriction in the cerebral circulation. However, we find that like 14,15-epoxyeicosatrienoic acid (14,15-EET), 20-HETE produces dilation of mouse basilar artery preconstricted with U-46619 in vitro. Indomethacin inhibited the vasodilation produced by 20-HETE but not by 14,15-EET, suggesting a cyclooxygenase (COX)-dependent mechanism. Metabolic studies indicated several mechanisms that may play a role in this process. Mouse brain endothelial cells (MBEC) converted 20-HETE to 20-OH-PGE(2), which was as potent as PGE(2) in dilating the basilar artery. 20-HETE also stimulated AA release and PGE(2) and 6-keto-PGF(1alpha) production in MBEC. Furthermore, the basilar artery converted 20-HETE to 20-COOH-AA, which also produced COX-dependent dilation of the basilar artery. 20-COOH-AA increased AA release and PGE(2) and 6-keto-PGF(1alpha) production by the MBEC, but to a lesser extent than 20-HETE. Whereas the conversion of 20-HETE to 20-OH-PGE(2) and production of endogenous prostaglandins probably are primarily responsible for vasodilation, the production of 20-COOH-AA also may contribute to this process.
AJP Heart and Circulatory Physiology 12/2006; 291(5):H2301-7. · 3.71 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Angiotensin II (Ang II) contributes to vascular pathology in part by stimulating NADPH oxidase activity, leading to increased formation of superoxide (O2-). We reported that O2- levels, NADPH oxidase activity, and expression of the p47phox subunit of NADPH oxidase are increased in human abdominal aortic aneurysms (AAAs). Here, we tested the hypothesis that deletion of p47phox will attenuate oxidative stress and AAA formation in Ang II-infused apoE-/- mice.
Male apoE-/- and apoE-/-p47phox-/- mice received saline or Ang II (1000 ng x kg(-1) x min(-1)) infusion for 28 days, after which abdominal aortic weight and maximal diameter were determined. Aortic tissues and blood were examined for parameters of aneurysmal disease and oxidative stress. Ang II infusion induced AAAs in 90% of apoE-/- versus 16% of apo-/-p47phox-/- mice (P < 0.05). Abdominal aortic weight (14.1 +/- 3.2 versus 35.6 +/- 9.0 mg), maximal aortic diameter (1.5 +/- 0.2 versus 2.4 +/- 0.4 mm), aortic NADPH oxidase activity, and parameters of oxidative stress were reduced in apoE-/-p47phox-/- mice compared with apoE-/- mice (P < 0.05). In addition, aortic macrophage infiltration and matrix metalloproteinase-2 activity were reduced in apoE-/-p47phox-/- mice compared with apoE-/- mice. Deletion of p47phox attenuated the pressor response to Ang II; however, coinfusion of phenylephrine with Ang II, which restored the Ang II pressor response, did not alter the protective effects of p47phox deletion on AAA formation.
Deletion of p47phox attenuates Ang II-induced AAA formation in apoE-/- mice, suggesting that NADPH oxidase plays a critical role in AAA formation in this model.
Circulation 09/2006; 114(5):404-13. · 14.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Hydrogen peroxide, produced by inflammatory and vascular cells, induces oxidative stress that may contribute to endothelial dysfunction. In smooth muscle cells, H(2)O(2) induces production of O(2)*(-) by activating NADPH oxidase. However, the mechanisms whereby H(2)O(2) induces oxidative stress in endothelial cells are poorly understood. We examined the effects of H(2)O(2) on O(2)*(-) levels on porcine aortic endothelial cells (PAEC). Treatment with 60 micromol/L H(2)O(2) markedly increased intracellular O(2)*(-) levels (determined by conversion of dihydroethidium to hydroxyethidium) and produced cytotoxicity (determined by propidium iodide staining) in PAEC. Overexpression of human manganese superoxide dismutase in PAEC reduced O(2)*(-) levels and attenuated cytotoxicity resulting from treatment with H(2)O(2). L-NAME, an inhibitor of nitric oxide synthase (NOS), and apocynin, an inhibitor of NADPH oxidase, reduced O(2)*(-) levels in PAEC treated with H(2)O(2), suggesting that both NOS and NADPH oxidase contribute to H(2)O(2)-induced O(2)*(-) in PAEC. Inhibition of NADPH oxidase using apocynin and NOS rescue with L-sepiapterin together reduced O(2)*(-) levels in PAEC treated with H(2)O(2) to control levels. This suggests interaction-distinct NOS and NADPH oxidase pathways to superoxide. We conclude that H(2)O(2) produces oxidative stress in endothelial cells by increasing intracellular O(2)*(-) levels through NOS and NADPH oxidase. These findings suggest a complex interaction between H(2)O(2) and oxidant-generating enzymes that may contribute to endothelial dysfunction.
Free Radical Biology and Medicine 07/2006; 40(12):2206-13. · 5.42 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Cardiovascular disease ranks among the leading causes of morbidity and mortality in adult populations in the Western world. Significant progress in understanding the etiology of cardiovascular disease has come from recent recognition that chronic inflammation plays a key role in its development. The principal mediators of this inflammatory response, and the mechanisms by which they work, however, are incompletely understood. Moreover, the complex nature of the inflammatory response poses significant challenges to the development of effective and targeted treatments. Potentially promising targets to reduce inflammation in atherosclerosis include Toll-like receptor (TLR) pathways and anti-inflammatory factors that modulate TLR signaling. In this review, we outline studies that provide insight into the links between cardiovascular disease and inflammation, focusing on innate immunity and endotoxin/TLR4 signaling. We also discuss the contribution of specific host immune/inflammatory responses to atherogenesis, and describe cellular signaling pathways (lipopolysaccharide-binding protein [LBP], CD14, MD-2, TLR4, MyD88, and NF-kappaB, among others) that play key roles in innate immune signaling. Finally, we discuss the therapeutic potential of modulating these cellular signaling pathways as future strategies for the prevention and treatment of cardiovascular disease, including such approaches as specific targeting of the TLR4 signaling pathway, antibiotic therapy, drug classes with broad anti-inflammatory activity (statins, thiazolidinediones), and the potential of vaccine development. Because of the complexity of the links between low-level chronic infections, inflammation, and atherosclerosis, treatment and prevention of cardiovascular disease will likely require an integrated approach that utilizes a combination of these strategies to target the underlying inflammatory processes.
Current pharmaceutical design 02/2006; 12(32):4229-45. · 4.41 Impact Factor
-
Xiang Fang,
Shanming Hu,
Bingkun Xu,
Gary D Snyder,
Shawn Harmon,
Jianrong Yao,
Yi Liu,
Bhavani Sangras,
J R Falck, Neal L Weintraub,
Arthur A Spector
[show abstract]
[hide abstract]
ABSTRACT: Epoxyeicosatrienoic acids (EETs), lipid mediators synthesized from arachidonic acid by cytochrome P-450 epoxygenases, are converted by soluble epoxide hydrolase (SEH) to the corresponding dihydroxyeicosatrienoic acids (DHETs). Originally considered as inactive degradation products of EETs, DHETs have biological activity in some systems. Here we examined the capacity of EETs and DHETs to activate peroxisome proliferator-activated receptor-alpha (PPARalpha). We find that among the EET and DHET regioisomers, 14,15-DHET is the most potent PPARalpha activator in a COS-7 cell expression system. Incubation with 10 microM 14,15-DHET produced a 12-fold increase in PPARalpha-mediated luciferase activity, an increase similar to that produced by the PPARalpha agonist Wy-14643 (20 microM). Although 10 microM 14,15-EET produced a threefold increase in luciferase activity, this was abrogated by the SEH inhibitor dicyclohexylurea. 14-Hexyloxytetradec-5(Z)-enoic acid, a 14,15-EET analog that cannot be converted to a DHET, did not activate PPARalpha. However, PPARalpha was activated by 2-(14,15-epoxyeicosatrienoyl)glycerol, which was hydrolyzed and the released 14,15-EET converted to 14,15-DHET. COS-7 cells incorporated 14,15-[3H]DHET from the medium, and the cells also retained a small amount of the DHET formed during incubation with 14,15-[3H]EET. Binding studies indicated that 14,15-[3H]DHET binds to the ligand binding domain of PPARalpha with a Kd of 1.4 microM. Furthermore, 14,15-DHET increased the expression of carnitine palmitoyltransferase 1A, a PPARalpha-responsive gene, in transfected HepG2 cells. These findings suggest that 14,15-DHET, produced from 14,15-EET by the action of SEH, may function as an endogenous activator of PPARalpha.
AJP Heart and Circulatory Physiology 02/2006; 290(1):H55-63. · 3.71 Impact Factor
-
Xixuan H Collins,
Shawn D Harmon,
Terry L Kaduce,
Kristine B Berst,
Xiang Fang,
Steven A Moore,
T Verugopal Raju,
John R Falck, Neal L Weintraub,
Gregg Duester,
Bryce V Plapp,
Arthur A Spector
[show abstract]
[hide abstract]
ABSTRACT: 20-Carboxyeicosatetraenoic acid (20-COOH-AA) is a bioactive metabolite of 20-hydroxyeicosatetraenoic acid (20-HETE), an eicosanoid that produces vasoconstriction in the cerebral circulation. We found that smooth muscle (MSMC) and endothelial (MEC) cultures obtained from mouse brain microvessels convert [3H]20-HETE to 20-COOH-AA, indicating that the cerebral vasculature can produce this metabolite. The [3H]20-COOH-AA accumulated primarily in the culture medium, together with additional radiolabeled metabolites identified as the chain-shortened dicarboxylic acids 18-COOH-18:4, 18-COOH-18:3, and 16-COOH-16:3. N-Heptylformamide, a potent inhibitor of alcohol dehydrogenase (ADH), decreased the conversion of [3H]20-HETE to 20-COOH-AA by the MSMC and MEC and also by isolated mouse brain microvessels. Purified mouse and human ADH4, human ADH3, and horse liver ADH1 efficiently oxidized 20-HETE, and ADH4 and ADH3 were detected in MSMC and MEC by Western blotting. N-Heptylformamide inhibited the oxidation of 20-HETE by mouse and human ADH4 but not by ADH3. These results demonstrated that cerebral microvessels convert 20-HETE to 20-COOH-AA and that ADH catalyzes the reaction. Although ADH4 and ADH3 are expressed in MSMC and MEC, the inhibition produced by N-heptylformamide suggests that ADH4 is primarily responsible for 20-COOH-AA formation in the cerebral microvasculature.
Journal of Biological Chemistry 10/2005; 280(39):33157-64. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Soluble epoxide hydrolase (sEH) plays a major role in regulating vascular epoxyeicosatrienoic acid metabolism and function, and substituted urea derivatives that inhibit sEH activity reduce blood pressure in hypertensive rats. We found that substituted urea derivatives containing a dodecanoic acid group, besides effectively inhibiting sEH, increased peroxisome proliferator-activated receptor (PPAR) alpha activity. In PPARalpha transfected COS-7 cells, treatment with 10 microM N-cyclohexyl-N'-dodecanoic acid urea (CUDA) or N-adamantanyl-N'-dodecanoic acid urea (AUDA) produced 6- and 3-fold increases, respectively, in PPARalpha activation. Neither CUDA nor AUDA activated PPARdelta or PPARgamma directly, indicating selectivity for PPARalpha. CUDA did not alter PPARalpha protein expression, and it competitively inhibited the binding of Wy-14643 (pirinixic acid) to the ligand binding domain of PPARalpha, suggesting that it functions as a PPARalpha ligand. CUDA and AUDA were metabolized to chain-shortened beta-oxidation products, a process that reduced their potency as sEH inhibitors and their ability to bind and activate PPARalpha. N,N'-Dicylclohexylurea and N-cyclohexyl-N'-dodecylurea, sEH inhibitors that do not contain a carboxylic acid group, did not activate PPARalpha. In HepG2 cells, CUDA increased the expression of the PPARalpha-responsive gene carnitine palmitoyltransferase 1A. We conclude that CUDA and AUDA, by virtue of their carboxylic acid substitution, activate PPARalpha in addition to potently inhibiting sEH. Further development of these compounds could lead to a class of agents with hypotensive and lipid-lowering properties that may be valuable for the prevention and treatment of cardiovascular disease.
Journal of Pharmacology and Experimental Therapeutics 08/2005; 314(1):260-70. · 3.83 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Abdominal aortic aneurysms (AAAs) in humans are associated with locally increased oxidative stress and activity of NADPH oxidase. We investigated the hypothesis that vitamin E, an antioxidant with documented efficacy in mice, can attenuate AAA formation during angiotensin II (Ang II) infusion in apolipoprotein E-deficient mice.
Six-month-old male apolipoprotein E-deficient mice were infused with Ang II at 1000 ng/kg per minute for 4 weeks via osmotic minipumps while consuming either a regular diet or a diet enriched with vitamin E (2 IU/g of diet). After 4 weeks, abdominal aortic weight and maximal diameter were determined, and aortic tissues were sectioned and examined using biochemical and histological techniques. Vitamin E attenuated formation of AAA, decreasing maximal aortic diameter by 24% and abdominal aortic weight by 34% (P<0.05, respectively). Importantly, animals treated with vitamin E showed a 44% reduction in the combined end point of fatal+nonfatal aortic rupture (P<0.05). Vitamin E also decreased aortic 8-isoprostane content (a marker of oxidative stress) and reduced both aortic macrophage infiltration and osteopontin expression (P<0.05, respectively). Vitamin E treatment had no significant effect on the extent of aortic root atherosclerosis, activation of matrix metalloproteinases 2 or 9, serum lipid profile, or systolic blood pressure.
Vitamin E ameliorates AAAs and reduces the combined end point of fatal+nonfatal aortic rupture in this animal model. These findings are consistent with the concept that oxidative stress plays a pivotal role in Ang II-driven AAA formation in hyperlipidemic mice.
Arteriosclerosis Thrombosis and Vascular Biology 08/2005; 25(8):1671-7. · 6.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We report a case of group F streptococcal pericarditis, the source of which was found to be an esophagomediastinal fistula arising from a midesophageal diverticulum. The patient presented subacutely and had no preexisting symptoms of esophageal disease. Antibiotic therapy, surgical drainage, pericardiectomy, and esophageal myotomy led to a successful outcome.
The Annals of thoracic surgery 07/2005; 79(6):2132-4. · 3.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Statins, a group of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, are widely used in clinical practice for their efficacy in producing significant reductions in plasma cholesterol and LDL cholesterol and in reducing morbidity and mortality from cardiovascular disease. However, several large clinical trials have suggested that the cholesterol-lowering effects of statins may not completely account for the reduced incidence of cardiovascular disease seen in patients receiving statin therapy. A number of recent reports have shown that statins may also have important antiinflammatory effects, in addition to their effects on plasma lipids. Since inflammation is closely linked to the production of reactive oxygen species (ROS), the molecular basis of the observed antiinflammatory effects of statins may relate to their ability block the production and/or activity of ROS. In this review, we will discuss both the inhibition of ROS generation by statins, through interference with NAD(P)H oxidase expression and activity, and the actions of statins that serve to blunt the damaging effects of these radicals, including effects on antioxidant enzymes, lipid peroxidation, LDL cholesterol oxidation and nitric oxide synthase. These antioxidant effects of statins likely contribute to their clinical efficacy in treating cardiovascular disease as well as other chronic conditions associated with increased oxidative stress in humans.
Timely topics in medicine. Cardiovascular diseases 02/2005; 9:E1.
-
[show abstract]
[hide abstract]
ABSTRACT: Atherosclerosis is increasingly recognized as a chronic inflammatory disease. Although a variety of inflammatory markers (ie, C-reactive protein) have been associated with atherosclerosis and its consequences, it is important to identify principal mediators of the inflammatory responses. One potentially important source of vascular inflammation in atherosclerosis is bacterial endotoxin. Mutations in Toll-like receptor 4 (TLR-4), an integral component of the endotoxin signaling complex, are fairly common in the Caucasian population and have recently been associated with reduced incidence of atherosclerosis and other cardiovascular diseases in some studies. Moreover, epidemiological studies suggest that endotoxemia at levels as low as 50 pg/mL constitutes a strong risk factor for the development of atherosclerosis. Endotoxin concentrations in this range may be produced by a variety of common subclinical Gram-negative infections. In this article, we outline the main elements of the endotoxin signaling receptor complex that initiates proinflammatory signaling (lipopolysaccharide binding protein [LBP], CD14, TLR-4, and MD-2) and discuss how changes in expression of these molecules may affect proatherogenic responses in the vessel wall. We also describe some of the proinflammatory effects of endotoxin that may be relevant to atherosclerosis, and discuss how serum lipoproteins, especially high-density lipoprotein, may modulate endotoxin-induced inflammatory responses. Further, we discuss recent findings suggesting that the lipid-lowering statins may have an additional protective role in blocking at least some of these proinflammatory signaling pathways. Finally, we discuss species diversity with regard to endotoxin signaling that should be considered when extrapolating experimental data from animal models to humans.
Arteriosclerosis Thrombosis and Vascular Biology 01/2005; 24(12):2227-36. · 6.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We investigated the effects of soluble epoxide hydrolase (sEH) inhibition on epoxyeicosatrienoic acid (EET) metabolism in intact human blood vessels, including the human saphenous vein (HSV), coronary artery (HCA), and aorta (HA). When HSV segments were perfused with 2 micromol/l 14,15-[3H]EET for 4 h, >60% of radioactivity in the perfusion medium was converted to 14,15-dihydroxyeicosatrienoic acid (DHET). Similar results were obtained with endothelium-denuded vessels. 14,15-DHET was released from both the luminal and adventitial surfaces of the HSV. When HSVs were incubated with 14,15-[3H]EET under static (no flow) conditions, formation of 14,15-DHET was detected within 15 min and was inhibited by the selective sEH inhibitors N,N'-dicyclohexyl urea and N-cyclohexyl-N'-dodecanoic acid urea (CUDA). Similarly, CUDA inhibited the conversion of 11,12-[3H]EET to 11,12-DHET by the HSV. sEH inhibition enhanced the uptake of 14,15-[3H]EET and facilitated the formation of 10,11-epoxy-16:2, a beta-oxidation product. The HCA and HA converted 14,15-[3H]EET to DHET, and this also was inhibited by CUDA. These findings in intact human blood vessels indicate that conversion to DHET is the predominant pathway for 11,12- and 14,15-EET metabolism and that sEH inhibition can modulate EET metabolism in vascular tissue.
AJP Heart and Circulatory Physiology 12/2004; 287(6):H2412-20. · 3.71 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Low-level endotoxemia has been identified as a powerful risk factor for atherosclerosis. However, little is known about the mechanisms that regulate endotoxin responsiveness in vascular cells. We conducted experiments to compare the relative responses of human coronary artery endothelial cells (HCAEC) and smooth muscle cells (HCASMC) to very low levels of endotoxin, and to elucidate the mechanisms that regulate endotoxin responsiveness in vascular cells. Endotoxin (</=1 ng/ml) caused production of chemotactic cytokines in HCAEC. Endotoxin-induced cytokine production was maximal at LPS-binding protein:soluble CD14 ratios <1, typically observed in individuals with subclinical infection; higher LPS-binding protein:soluble CD14 ratios were inhibitory. Endotoxin potently activated HCASMC, with cytokine release >10-fold higher in magnitude at >10-fold lower threshold concentrations (10-30 pg/ml) compared with HCAEC. This remarkable sensitivity of HCASMC to very low endotoxin concentrations, comparable to that found in circulating monocytes, was not due to differential expression of TLR4, which was detected in HCAEC, HCASMC, and intact coronary arteries. Surprisingly, membrane-bound CD14 was detected in seven different lines of HCASMC, conferring responsiveness to endotoxin and to lipoteichoic acid, a product of Gram-positive bacteria, in these cells. These results suggest that the low levels of endotoxin associated with increased risk for atherosclerosis are sufficient to produce inflammatory responses in coronary artery cells. Because CD14 recognizes a diverse array of inflammatory mediators and functions as a pattern recognition molecule in inflammatory cells, expression of membrane-bound CD14 in HCASMC implies a potentially broader role for these cells in transducing innate immune responses in the vasculature.
The Journal of Immunology 07/2004; 173(2):1336-43. · 5.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Ghrelin is a novel growth hormone-releasing peptide that has been shown to improve cachexia in heart failure and cancer and to ameliorate the hemodynamic and metabolic disturbances in septic shock. Because cytokine-induced inflammation is critical in these pathological states and because the growth hormone secretagogue receptor has been identified in blood vessels, we examined whether ghrelin inhibits proinflammatory responses in human endothelial cells in vitro and after administration of endotoxin to rats in vivo.
Human umbilical vein endothelial cells (HUVECs) were treated with or without tumor necrosis factor-alpha (TNF-alpha), and induction of proinflammatory cytokines and mononuclear cell adhesion were determined. Ghrelin (0.1 to 1000 ng/mL) inhibited both basal and TNF-alpha-induced cytokine release and mononuclear cell binding. Intravenous administration of ghrelin also inhibited endotoxin-induced proinflammatory cytokine production in rats in vivo. Ghrelin inhibited H2O2-induced cytokine release in HUVECs, suggesting that the peptide blocks redox-mediated cellular signaling. Moreover, ghrelin inhibited basal and TNF-alpha-induced activation of nuclear factor-kappaB. Des-acyl ghrelin had no effect on TNF-alpha-induced cytokine production in HUVECs, suggesting that the antiinflammatory effects of ghrelin require interaction with endothelial growth hormone secretagogue receptors.
Ghrelin inhibits proinflammatory cytokine production, mononuclear cell binding, and nuclear factor-kappaB activation in human endothelial cells in vitro and endotoxin-induced cytokine production in vivo. These novel antiinflammatory actions of ghrelin suggest that the peptide could play a modulatory role in atherosclerosis, especially in obese patients, in whom ghrelin levels are reduced.
Circulation 06/2004; 109(18):2221-6. · 14.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Ghrelin, an endogenous ligand of the growth hormone secretagogue receptor, has been reported to have beneficial effects on cardiac function. The authors used the Langendorff model of ischemia/reperfusion (I/R) injury in isolated rat heart to determine whether ghrelin exerts direct cardioprotective effects. Also, the capacity of ghrelin to bind to sarcolemmal membrane fractions before and after ischemia and reperfusion was examined. Compared with vehicle administration, administration of ghrelin (100-10,000 pM) during the reperfusion period resulted in improvement in coronary flow, heart rate, left ventricular systolic pressure, and left ventricular end-diastolic pressure. Ghrelin also enhanced the rates of left ventricular contraction and relaxation after ischemia following reperfusion. Administration of ghrelin during reperfusion reduced myocardial release of lactate dehydrogenase and myoglobin, indicating protection against cardiomyocyte injury. In addition, ghrelin attenuated the depletion of myocardial ATP resulting from ischemia and reperfusion. A receptor-binding assay demonstrated that maximum binding capacity of ghrelin to sarcolemmal membranes was significantly increased after ischemia and was further increased after I/R. However, Scatchard analysis showed that the affinity of ghrelin for its receptor was not altered. The authors have concluded that administration of ghrelin during reperfusion protects against myocardial I/R injury. The cardioprotective effects are independent of growth hormone release and likely involve binding to cardiovascular receptors, a process that is upregulated during I/R.
Journal of Cardiovascular Pharmacology 03/2004; 43(2):165-70. · 2.29 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Human cytomegalovirus (CMV) is a possible co-factor in atherogenesis and vascular occlusion, but its ability to actively infect medium and large blood vessels is unclear. A vascular explant model was adapted to investigate CMV infection in human coronary artery, internal mammary artery (IMA), and saphenous vein (SV). Vascular explants were inoculated with CMV Towne or low-passage clinical isolate and examined in situ for CMV cytopathic effect and immediate-early and early antigens, as indicators of active infection. At 5 to 7 days after inoculation, we found that CMV Towne actively infected eight of eight different atherosclerotic blood vessel explants (coronary artery, n = 4; SV and IMA grafts, n = 4), whereas it only infected 2 of 14 nonatherosclerotic blood vessel explants (SV, n = 10; IMA, n = 4) (P = 0.001). The CMV clinical isolate actively infected none of six sets of nonatherosclerotic SV explants at 5 to 7 days after inoculation. The active CMV infections involved adventitial and, less frequently, intimal cells. A small subset of infected cells in atherosclerotic tissue expresses the endothelial cell marker CD31. Smooth muscle cells residing in both atherosclerotic and nonatherosclerotic blood vessels were free of active CMV infections even after all vascular tissue layers were exposed to the virus. In contrast, active CMV Towne infection was evident at 2 days after inoculation in smooth muscle cells and endothelial cells previously isolated from the SV tissues. We conclude that active CMV infection is enhanced in atherosclerotic blood vessels compared to atherosclerosis-free vascular equivalents, and this viral activity is restricted to subpopulations of intimal and adventitial cells.
American Journal Of Pathology 03/2004; 164(2):589-600. · 4.89 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Epoxyeicosatrienoic acids (EETs), which are synthesized from arachidonic acid by cytochrome P450 epoxygenases, function primarily as autocrine and paracrine effectors in the cardiovascular system and kidney. They modulate ion transport and gene expression, producing vasorelaxation as well as anti-inflammatory and pro-fibrinolytic effects. EETs are incorporated into the sn-2 position of phospholipids and are rapidly mobilized when a cell is treated with a Ca(2+) ionophore, suggesting that they may play a role in phospholipid-mediated signal transduction processes. Soluble epoxide hydrolase (sEH) converts EETs to dihydroxyeicosatrienoic acids (DHETs), and inhibition of sEH is a potential approach for enhancing the biological activity of EETs. EETs also undergo chain-elongation and beta-oxidation, and the accumulation of partial beta-oxidation products increases when sEH is inhibited. Some functional effects of EETs occur through activation of either the guanine nucleotide binding protein Galphas or the Src signal transduction pathways, suggesting that EETs act by binding to membrane receptors. However, other evidence indicates that the modulation of gene expression occurs through an intracellular action of EETs. Because of the diversity of biochemical and functional responses produced by EETs, it is doubtful that a single mechanism or signal transduction pathway can account for all of their actions.
Progress in Lipid Research 02/2004; 43(1):55-90. · 10.67 Impact Factor
-
Terry L Kaduce,
Xiang Fang,
Shawn D Harmon,
Christine L Oltman,
Kevin C Dellsperger,
Lynn M Teesch,
V Raj Gopal,
J R Falck,
William B Campbell, Neal L Weintraub,
Arthur A Spector
[show abstract]
[hide abstract]
ABSTRACT: We have investigated the role of endothelial cells in the metabolism of 20-hydroxyeicosatetraenoic acid (20-HETE), a vasoactive mediator synthesized from arachidonic acid by cytochrome P450 omega-oxidases. Porcine coronary artery endothelial cells (PCEC) incorporated 20-[(3)H]HETE primarily into the sn-2 position of phospholipids through a coenzyme A-dependent process. The incorporation was reduced by equimolar amounts of arachidonic, eicosapentaenoic or 8,9-epoxyeicosatrienoic acids, but some uptake persisted even when a 10-fold excess of arachidonic acid was available. The retention of 20-[(3)H]HETE increased substantially when methyl arachidonoyl fluorophosphonate, but not bromoenol lactone, was added, suggesting that a Ca(2+)-dependent cytosolic phospholipase A(2) released the 20-HETE contained in PCEC phospholipids. Addition of calcium ionophore A23187 produced a rapid release of 20-[(3)H]HETE from the PCEC, a finding that also is consistent with a Ca(2+)-dependent mobilization process. PCEC also converted 20-[(3)H]HETE to 20-carboxy-arachidonic acid (20-COOH-AA) and 18-, 16-, and 14-carbon beta-oxidation products. 20-COOH-AA produced vasodilation in porcine coronary arterioles, but 20-HETE was inactive. These results suggest that the incorporation of 20-HETE and its subsequent conversion to 20-COOH-AA in the endothelium may be important in modulating coronary vascular function.
Journal of Biological Chemistry 02/2004; 279(4):2648-56. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Reactive oxygen species (ROS) have been proposed to mediate vasodilation in the microcirculation. We investigated the role of ROS in arachidonic acid (AA)-induced coronary microvascular dilation. Porcine epicardial coronary arterioles (110 +/- 4 microm diameter) were mounted onto pipettes in oxygenated Krebs buffer. Vessels were incubated with vehicle or 1 mM Tiron (a nonselective ROS scavenger), 250 U/ml polyethylene-glycolated (PEG)-superoxide dismutase (SOD; an O2- scavenger), 250 U/ml PEG-catalase (a H2O2 scavenger), or the cyclooxygenase (COX) inhibitors indomethacin (10 microM) or diclofenac (10 microM) for 30 min. After endothelin constriction (30-60% of resting diameter), cumulative concentrations of AA (10(-10)-10(-5)M) were added and internal diameters measured by video microscopy. AA (10-7 M) produced 37 +/- 6% dilation, which was eliminated by the administration of indomethacin (4 +/- 7%, P < 0.05) or diclofenac (-8 +/- 8%, P < 0.05), as well as by Tiron (-4 +/- 5%, P < 0.05), PEG-SOD (-10 +/- 6%, P < 0.05), or PEG-catalase (1 +/- 4%, P < 0.05). Incubation of small coronary arteries with [3H]AA resulted in the formation of prostaglandins, which was blocked by indomethacin. In separate studies in microvessels, AA induced concentration-dependent increases in fluorescence of the oxidant-sensitive probe dichlorodihydrofluorescein diacetate, which was inhibited by pretreatment with indomethacin or by SOD + catalase. We conclude that in porcine coronary microvessels, COX-derived ROS contribute to AA-induced vasodilation.
AJP Heart and Circulatory Physiology 12/2003; 285(6):H2309-15. · 3.71 Impact Factor
