Biomedical subjects

Martin Rodriguez-Porcel

Publications and source records attributed to Martin Rodriguez-Porcel.

At least 19 recordsLinked to original sources

PubMed2006

Redox-sensitive myocardial remodeling and dysfunction in swine diet-induced experimental hypercholesterolemia.

OBJECTIVES: The effects of hypercholesterolemia (HC) on the myocardium and the underlying mechanisms are unclear. We tested the hypothesis that diet-induced HC-induced myocardial fibrosis by regulating the transforming growth factor (TGF)-beta pathway and apoptosis through increased oxidative stress, and that these would be functionally consequential. METHODS: Three groups of pigs (n=6 each) were studied after 12 weeks of normal or 2% HC diet, or HC+antioxidant supplementation. Cardiac function was evaluated by electron beam computed tomography, while fibrogenic mechanisms and apoptosis were evaluated in myocardial tissue. RESULTS: HC-induced myocardial fibrosis was accompanied by increased ratio of interstitial collagen I/III (1.4+/-0.3 versus 0.5+/-0.1 in normal, p<0.05), expression of TGF-beta1 and its downstream smad mediators, as well as myocyte apoptosis. These alterations were also associated with a decrease in diastolic filling rate compared to normal (134.0+/-10.6 ml/s versus 70.3+/-14.3 ml/s, p<0.05), but were attenuated in HC animals chronically supplemented with antioxidants. CONCLUSIONS: Myocardial injury elicited by experimental HC includes redox-sensitive increases in TGF-beta1 expression and apoptosis, which are associated with diastolic dysfunction. These observations underscore a role of increased oxidative stress in modulating myocardial tissue remodeling and dysfunction in vivo in HC.

Animals↗

PubMed2006

Role of oxidative stress in remodeling of the myocardial microcirculation in hypertension.

OBJECTIVE: We tested the hypothesis that in early hypertension (HT), increased oxidative stress leads to myocardial microvascular remodeling. METHODS AND RESULTS: Pigs were studied after a 12-week observation: normal (n=8), untreated renovascular HT (n=8), or HT+chronic antioxidant supplementation (HT+A, n=6). Left ventricular muscle mass (LVMM) and myocardial blood flow (MBF) reserve were determined using electron beam computer tomography (CT), and the spatial density and tortuousity of myocardial microvessels (<500 microm) was then measured in myocardial samples with micro-CT. Myocardial microvascular morphology, oxidative stress, inflammation, and growth factor expression were determined in vitro. HT and HT+A had similarly increased arterial pressure and LVMM, but only HT showed impaired MBF response to adenosine. Compared with normal, HT had increased spatial density of myocardial microvessels, which was preserved in HT+A (111.8+/-7.8, 166.3+/-15.7, and 106.4+/-6.1 vessels per cm2, respectively). HT also showed microvascular wall thickening, increased systemic and tissue oxidative stress, inflammation, and expression of vascular endothelial growth factor and its receptor Flk-1, most of which were attenuated by antioxidants. CONCLUSIONS: Myocardial microvascular remodeling in early HT is accompanied by tissue oxidative stress, inflammation, and altered growth factor expression, and attenuated by antioxidant intervention. This study underscores a role of increased oxidative stress in modulating myocardial microvascular architecture in early HT.

Animals↗

PubMed2006

Chronic antioxidant supplementation impairs coronary endothelial function and myocardial perfusion in normal pigs.

Experimental studies have shown the beneficial effects of antioxidant supplementation on endothelial function in the presence of increased endogenous oxidative stress, whereas limited data are available under normal conditions. The present study tested the hypothesis that in normal pigs long-term antioxidants would have deleterious effects on the cardiovascular system. Normal domestic pigs (V, n=6) were studied 12 weeks after dietary supplementation with vitamin E (100 IU/kg per day) and vitamin C (1 g/day) and compared with normal controls (C, n=7). Myocardial perfusion and permeability index were evaluated by electron beam computed tomography after intravenous adenosine and dobutamine. Coronary endothelial function was evaluated in vitro by organ chamber and coronary tissue studied by immunoblotting and staining. Myocardial perfusion response was lower in V than in C after adenosine (10.1+/-4.5 versus 53.4+/-5.2%; P<0.01) and dobutamine (V, 78.4+/-8.1; C, 193.0+/-39.0%; P<0.05). The permeability index increased in V after adenosine (48.8+/-5.1%) and dobutamine (59.9+/-13.6%) and did not change in C. Coronary vasodilation to bradykinin and substance P was lower in V than in C. Moreover, in V, coronary nitrotyrosine and superoxide content was significantly higher than in C. The groups had similar total monomer expression of endothelial nitric oxide synthase, whereas the dimerized form, reflecting coupled enzyme, was lower in V. These findings suggest that long-term experimental antioxidant vitamin supplementation in normal pigs impairs myocardial perfusion and coronary endothelial function via an increased level of oxidative stress in the arterial wall, which may be partly related to the uncoupling of endothelial nitric oxide synthase and/or the direct prooxidant effect of vitamin radicals.

Animals↗

PubMed2005

Dietary reversal of experimental hypercholesterolemia improves endothelial dysfunction of epicardial arteries but not of small coronary vessels in pigs.

Endothelial dysfunction is characterized by impaired vasodilation, increase of oxidative stress and inflammation. The current study was designed to test the hypothesis that reversal of hypercholesterolemic diet alone does not normalize all the parameters of endothelial dysfunction. After 10 weeks on a high-cholesterol diet, female juvenile pigs were randomized to normal diet (n=5, "Reversals") or continued on the same diet (n=6, "HC") for another 6 weeks. A control group of 11 pigs received a normal diet ("C"). Coronary epicardial and arteriolar endothelial function was tested in vitro. NFkappaB and p47phox expression was analyzed in epicardial arteries and myocardium, respectively. P47phox localization in coronary arteries was demonstrated with immunohistochemistry. Lipid levels normalized in Reversal pigs. Epicardial arteries of Reversals showed a normalized relaxation and NFkappaB expression compared to HC (p<0.05). Small vessel relaxation remained attenuated, and expression of p47phox in myocardial tissue was elevated in Reversals compared to C (p<0.05). Dietary lowering of serum cholesterol and LDL improves vascular function of epicardial arteries but neither of small vessels nor vascular oxidative stress within this time frame. Hence, dietary normalization of serum lipid levels alone may not be synonymous to normalization of the components of endothelial dysfunction.

Analysis of Variance↗

PubMed2005

Functional and structural remodeling of the myocardial microvasculature in early experimental hypertension.

Advanced hypertension (HT), associated with left ventricular hypertrophy (LVH), impairs myocardial microvascular function and structure and leads to increased myocardial hypoxia and growth factor activation. However, the effect of HT on microvascular architecture and its relation to microvascular function, before the development of LVH (early HT), remains unclear. By way of method, pigs were studied after 12 wk of renovascular HT (n = 7) or control (n = 7) animals. Myocardial microvascular function (blood volume and blood flow at baseline and in response to adenosine) was assessed by using electron beam computed tomography (CT). Microvascular architecture was subsequently studied ex vivo using micro-CT, and microvessels (diameter, <500 microm) were counted in situ in three-dimensional images (40-microm on-a-side cubic voxels). Myocardial expression of vascular endothelial growth factor, basic fibroblast growth factor, and hypoxia-inducible factor-1alpha were also measured. By way of results, left ventricular muscle mass was similar between the groups. The blood volume response to intravenous adenosine was attenuated in HT animals compared with normal animals (+7.4 +/- 17.0 vs. +46.2 +/- 12.3% compared with baseline, P = 0.48 and P = 0.01, respectively). Microvascular spatial density in HT animals was significantly elevated compared with normal animals (246 +/- 26 vs. 125 +/- 20 vessels/cm2, P < 0.05) and correlated inversely with the blood volume response to adenosine. Growth factors expression was increased in HT animals compared with control animals. In conclusion, early HT elicits changes in myocardial microvascular architecture, which are associated with microvascular dysfunction and precede changes in muscle mass. These observations underscore the direct and early effects of HT on the myocardial vasculature.

Animals↗

PubMed2005

Pathways of renal fibrosis and modulation of matrix turnover in experimental hypercholesterolemia.

Dyslipidemia often accompanies and accelerates renal disease, partly by promoting fibrosis. However, the mechanisms mediating this effect are unclear. We hypothesized that hypercholesterolemia modulates several interlinked pathways that promote deposition and blunt degradation of extracellular matrix, and that these could be manipulated by reversal of hypercholesterolemia. Fourteen pigs were fed a 16-week 2% high-cholesterol diet (HC-HC; n=7) or normal diet (n=7), whereas in 7 others, a 10-week HC was followed by a 6-week normal diet (HC-N). Renal endothelial function was assessed in vivo with electron-beam computed tomography, and renal tissue was then studied ex vivo using Western blot, real-time quantitative polymerase chain reaction, gelatin zymography, and immunostaining. HC-HC kidneys showed endothelial dysfunction, accompanied by increased intrarenal oxidative stress, inflammation, activation of the endothelin and transforming-growth factor-beta systems, and decreased matrix metalloproteinase expression and activity. Accordingly, HC-HC kidneys showed increased collagen IV expression and fibrosis. A lipid-lowering dietary intervention reversed most of these changes. In conclusion, this study indicates that renal fibrosis in early atherosclerosis is a result of a simultaneous increase in extracellular matrix deposition and blunted matrix metalloproteinase-mediated degradation, overall promoting perivascular and tubulointerstitial fibrosis. Notably, many of these pathways may be reversible in hypercholesterolemia, and crucial targets could potentially be identified for early interventions to preserve the kidney.

Animals↗

PubMed2005

Image-guided cardiac cell delivery using high-resolution small-animal ultrasound.

Open-chest cardiac injection is the preferred delivery method for cardiac gene and stem cell therapy in small animals, but it is invasive and the operator is unable to see the actual delivery site. High-resolution ultrasound has recently been developed for small-animal imaging. We tested the hypothesis that image-guided cardiac cell delivery using high-resolution ultrasound guidance is feasible and reproducible. Sprague-Dawley rats (n = 11) were imaged using high-resolution ultrasound, and stably transfected cardiomyoblasts (plasmid-CMV-firefly luciferase) were injected into the anterior cardiac wall under ultrasound guidance (parasternal long-axis view), using a 28-gauge needle. After injection, bioluminescence imaging was performed using a cooled charged-coupled camera. Injection was successful in all animals and was associated with no mortality. The signal detected was positively correlated with the amount of cells transplanted (R(2) = 0.94, P = 0.03) and highly correlated with ex vivo assays (R(2) = 0.82). In addition, the optical signal could be followed longitudinally using bioluminescence imaging. Ultrasound image-guided cardiac cell delivery is an effective, safe, and reproducible way to perform cell delivery to a specific myocardial region and can be combined with assessment of cardiac function. We are confident that the use of these technologies will play a significant role in the future of gene and cell therapy.

Animals↗

PubMed2004

Cortical microvascular remodeling in the stenotic kidney: role of increased oxidative stress.

OBJECTIVE: Mechanisms of renal injury distal to renal artery stenosis (RAS) remain unclear. We tested the hypothesis that it involves microvascular remodeling consequent to increased oxidative stress. METHODS AND RESULTS: Three groups of pigs (n=6 each) were studied after 12 weeks of RAS, RAS+antioxidant supplementation (100 IU/kg vitamin E and 1 g vitamin C daily), or controls. The spatial density and tortuousity of renal microvessels (<500 microm) were tomographically determined by 3D microcomputed tomography. The in situ production of superoxide anion and the expression of vascular endothelial growth factor (VEGF), its receptor VEGFR-2, hypoxia-inducible-factor (HIF)-1alpha, von Hippel-Lindau (VHL) protein, and NAD(P)H oxidase (p47phox and p67phox subunits) were determined in cortical tissue. RAS and RAS+antioxidant groups had similar degrees of stenosis and hypertension. The RAS group showed a decrease in spatial density of cortical microvessels, which was normalized in the RAS+antioxidant group, as was arteriolar tortuousity. RAS kidneys also showed tissue fibrosis (by trichrome and Sirius red staining), increased superoxide anion abundance, NAD(P)H oxidase, VHL protein, and HIF-1alpha mRNA expression. In contrast, expression of HIF-1alpha, VEGF, and VEGFR-2 protein was downregulated. These were all significantly improved by antioxidant intervention. CONCLUSIONS: Increased oxidative stress in the stenotic kidney alters growth factor activity and plays an important role in renal microvascular remodeling, which can be prevented by chronic antioxidant intervention.

Animals↗

PubMed2004

Antioxidant intervention attenuates myocardial neovascularization in hypercholesterolemia.

BACKGROUND: Hypercholesterolemia (HC) and atherosclerosis can elicit oxidative stress, coronary endothelial dysfunction, and myocardial ischemia, which may induce growth-factor expression and lead to myocardial neovascularization. We tested the hypothesis that chronic antioxidant intervention in HC would attenuate neovascularization and preserve the expression of hypoxia-inducible factor (HIF)-1alpha and vascular endothelial growth factor (VEGF). METHODS AND RESULTS: Three groups of pigs (n=6 each) were studied after 12 weeks of normal or 2% HC diet or HC+antioxidant supplementation (100 IU/kg vitamin E and 1 g vitamin C daily). Myocardial samples were scanned ex vivo with a novel 3D micro-CT scanner, and the spatial density and tortuosity of myocardial microvessels were determined in situ. VEGF mRNA, protein levels of VEGF and VEGF receptor-1, HIF-1alpha, nitrotyrosine, and superoxide dismutase (SOD) were determined in myocardial tissue. The HC and HC+antioxidant groups had similar increases in serum cholesterol levels. HC animals showed an increase in subendocardial spatial density of microvessels compared with normal (160.5+/-11.8 versus 95.3+/-8.2 vessels/cm2, P<0.05), which was normalized in HC+antioxidant (92.5+/-20.5 vessels/cm2, P<0.05 versus HC), as was arteriolar tortuosity. In addition, HC induced upregulation of VEGF, HIF-1alpha, and nitrotyrosine expression and decreased SOD expression and activity, all of which were preserved by antioxidant intervention. CONCLUSIONS: Changes in myocardial microvascular architecture invoked by HC are accompanied by increases in HIF-1alpha and VEGF expression and attenuated by antioxidant intervention. This underscores a role of increased oxidative stress in modulating myocardial microvascular architecture in early atherogenesis.

Animals↗

PubMed2004

Comparison of acute and chronic antioxidant interventions in experimental renovascular disease.

Reactive oxygen species (ROS) can modulate renal hemodynamics and function both directly, by leading to vasoconstriction, and indirectly, by inducing renal inflammation and tissue growth. The involvement of oxidative stress in the pathogenesis of renovascular disease (RVD) is increasingly recognized, but the relative contribution of long-term tissue injury to renal dysfunction remains unclear. We hypothesized that functional and structural alterations elicited by oxidative stress in RVD would be more effectively modulated by chronic than by acute antioxidant intervention. Renal hemodynamics and function were quantified in vivo in pigs using electron-beam computed tomography at baseline and after vasoactive challenge (ACh and sodium nitroprusside); after 12 wk of RVD (simulated by concurrent hypercholesterolemia and renal artery stenosis, n = 7); RVD acutely infused with the SOD-mimetic tempol (RVD+tempol, n = 7); RVD chronically supplemented with antioxidant vitamins C (1 g) and E (100 IU/kg; RVD+vitamins, n = 7); or control (normal, n = 7). Renal tissue was studied ex vivo using immunoblotting and immunohistochemistry. Basal renal blood flow (RBF) and glomerular filtration rate were similarly decreased in all RVD groups. ACh-stimulated RBF remained unchanged in RVD, increased in RVD+tempol, but further increased (similarly to normal) in RVD+vitamins (P < 0.05 vs. RVD). Furthermore, RVD+vitamins also showed a decreased presence of superoxide anion, decreased NAD(P)H-oxidase and nitrotyrosine expression, increased endothelial nitric oxide synthase expression, and attenuated renal fibrosis. Chronic antioxidant intervention in early RVD improved renal hemodynamic responses more effectively than acute intervention, likely due to increased nitric oxide bioavailability and decreased structural injury. These suggest that chronic tissue changes play an important role in renal compromise mediated by oxidative stress in RVD.

Acetylcholine↗

PubMed2004

Long-term antioxidant intervention improves myocardial microvascular function in experimental hypertension.

Hypertension increases oxidative stress, which can impair myocardial microvascular function and integrity. However, it is yet unclear whether long-term antioxidant intervention in early hypertension would preserve myocardial perfusion and vascular permeability responses to challenge. Pigs were studied after 12 weeks of renovascular hypertension without (n=8) or with daily supplementation of antioxidants (100 IU/kg vitamin E and 1 g vitamin C, n=6), and compared with normal controls (n=7). Myocardial perfusion and microvascular permeability were measured in vivo by electron beam computed tomography before and after 2 cardiac challenges (intravenous adenosine and dobutamine). Basal left ventricular muscle mass was also obtained. Mean arterial pressure was significantly increased in both groups of hypertensive animals (without and with antioxidants, 123+/-9 and 126+/-4 mm Hg, respectively, versus normal, 101+/-4 mm Hg; both P<0.05), but muscle mass was not different among the groups. The impaired myocardial perfusion response to adenosine observed in hypertensives (normal, +51+/-14%; P<0.05 versus baseline; hypertension, +14+/-15%; P=0.3 versus baseline) was preserved in hypertensive pigs that received antioxidants (+44+/-15%; P=0.01 compared with baseline). Long-term antioxidant intervention also preserved subendocardial microvascular permeability responses in hypertension. On the other hand, antioxidant intervention had little effect on the hypertension-induced myocardial vascular dysfunction observed in response to dobutamine. This study demonstrates that the impaired myocardial perfusion and permeability responses to increased cardiac demand in early hypertension are significantly improved by long-term antioxidant intervention. These results support the involvement of oxidative stress in myocardial vascular dysfunction in hypertension and suggest a role for antioxidant strategies to preserve the myocardial microvasculature.

Animals↗

PubMed2004

Antioxidant intervention blunts renal injury in experimental renovascular disease.

Atherosclerotic renovascular disease (RVD) amplifies damage in a stenotic kidney by inducing pro-inflammatory mechanisms and disrupting tissue remodeling. Oxidative stress is increased in RVD, but its direct contribution to renal injury has not been fully established. The authors hypothesized that chronic antioxidant intervention in RVD would improve renal function and attenuate tissue injury. Single-kidney hemodynamics and function at baseline and during vasoactive challenge were quantified using electron-beam computed tomography in pigs after 12 wk of experimental RVD (simulated by concurrent hypercholesterolemia and renal artery stenosis, n = 7), RVD daily supplemented with antioxidant vitamins C (1 g), and E (100 IU/kg) (RVD+Vitamins, n = 7), or controls (normal, n = 7). Renal tissue was studied ex vivo using Western blot analysis and immunohistochemistry. Basal renal blood flow (RBF) and glomerular filtration rate (GFR) were similarly decreased in the stenotic kidney of both RVD groups. RBF and GFR response to acetylcholine was blunted in RVD, but significantly improved in RVD+Vitamins (P < 0.05 versus RVD). RVD+Vitamins also showed increased renal expression of endothelial nitric oxide synthase (eNOS) and decreased expression of NAD(P)H-oxidase, nitrotyrosine, inducible-NOS, and NF-kappaB, suggesting decreased superoxide abundance and inflammation. Furthermore, decreased expression of pro-fibrotic factors in RVD+Vitamins was accompanied by augmented expression of extracellular (matrix metalloproteinase-2) and intracellular (ubiquitin) protein degradation systems, resulting in significantly attenuated glomerulosclerosis and renal fibrosis. In conclusion, chronic antioxidant intervention in early experimental RVD improved renal functional responses, enhanced tissue remodeling, and decreased structural injury. This study supports critical pathogenic contribution of increased oxidative stress to renal injury and scarring in RVD and suggests a role for antioxidant strategies in preserving the atherosclerotic and ischemic kidney.

Acetylcholine↗

PubMed2004

Antioxidant intervention prevents renal neovascularization in hypercholesterolemic pigs.

Experimental hypercholesterolemia (HC) may lead to microvascular neovascularization, but the underlying pathogenic mechanism remains unclear. We tested the hypothesis that HC-induced intra-renal neovascularization is associated with inflammation and increased oxidative stress, and would be prevented by chronic antioxidant intervention. Kidneys were excised from pigs after a 12-wk normal (n = 10) or HC diet (n = 8), or HC diet supplemented daily with antioxidant vitamins C (1 g) and E (100 IU/kg) (HC + vitamins, n = 7). Renal cortical samples were then scanned three dimensionally with micro-computed tomography, and microvessels were counted in situ. Blood and tissue samples were removed for measurements of superoxide dismutase (SOD) activity, protein expression of the NADP(H)-oxidase subunits gp91phox, p47phox, and p67phox, vascular endothelial growth factor (VEGF) levels and mRNA, VEGF receptors (Flt-1 and Flk-1), the proinflammatory transcription factor NFkappaB, and the oxidized LDL receptor LOX-1. Microvascular spatial density was significantly elevated in HC compared with normal kidneys but preserved in HC + vitamins. Expression of gp91phox and p67phox was decreased in HC pigs after antioxidant intervention, and SOD improved. The increased renal expression of VEGF and Flk-1 in HC was blunted in HC + vitamins, as were the significant increases in LOX-1, NFkappaB, and interstitial fibrosis. This study shows that renal cortical neovascularization elicited by diet-induced HC is associated with renal inflammation, fibrosis, and upregulation of VEGF and its receptor Flk-1, likely mediated by increased endogenous oxidative stress. Chronic antioxidant supplementation may preserve the kidney in HC.

Animals↗

PubMed2003

Beneficial effects of antioxidant vitamins on the stenotic kidney.

Renal artery stenosis (RAS) may lead to renal injury, partly mediated through increased oxidative stress. However, the potential effects of chronic oral antioxidant intervention on the stenotic kidney remain unknown. This study was designed to test the hypothesis that chronic antioxidant vitamin supplementation in RAS would preserve renal function and structure. Single-kidney hemodynamics and function were quantified in vivo in pigs using electron-beam CT after 12 weeks of unilateral RAS (n=7), a similar degree of RAS orally supplemented with vitamins C (1 g) and E (100 IU/kg) (RAS+Vitamins, n=7), or controls (normal, n=7). Renal tissue was studied ex vivo using Western blotting and immunohistochemistry. Mean arterial pressure was similarly elevated in both RAS groups, while ischemic renal volume and glomerular filtration rate were similarly reduced. Renal blood flow was decreased in RAS compared with normal (326.5+/-99.9 versus 553.4+/-48.7 mL/min, respectively, P=0.01), but preserved in RAS+Vitamins (485.2+/-104.1 mL/min, P=0.3 versus normal). The marked increase in the expression of the NADPH-oxidase subunits p47phox and p67phox, nitrotyrosine, endothelial and inducible nitric oxide synthase, and nuclear factor-kappaB observed in RAS (P<0.05 versus normal) was normalized in RAS+Vitamins (P>0.1). Furthermore, trichrome staining and the expression of transforming growth factor-beta and tissue inhibitor of matrix-metalloproteinase-1 were also decreased in RAS+Vitamins. In conclusion, chronic blockade of the oxidative stress pathway in RAS using antioxidant vitamins improved renal hemodynamics and decreased oxidative stress, inflammation, and fibrosis in the ischemic kidney. These observations underscore the involvement of oxidative stress in renal injury in RAS and support a role for antioxidant vitamins in preserving the ischemic kidney.

Animals↗

PubMed2003

Oxidative stress-related increase in ubiquitination in early coronary atherogenesis.

The ubiquitin-proteasome system (UPS) is involved in the removal of damaged proteins and the activation of transcription factors, such as nuclear-factor-kappaB. Recent reports, however, questioned the functional activity of the UPS under conditions of increased oxidative stress, such as experimental hypercholesterolemia, which was the objective of our study. Pigs were placed on a normal chow diet (N) or on a hypercholesterolemic diet without (HC) or with vitamin C and E supplementation (HC+VIT) for 12 weeks. Compared with N, plasma concentration of total cholesterol increased in both HC and HC+VIT [76 +/- 21 vs. 400 +/- 148 (P<0.05) and 329 +/- 102 (P<0.05) mg/dL], whereas increase in lipid peroxidation, as assessed by LDL-malondialdehyde plasma concentration, was found in HC but not in HC+VIT [6.6 +/- 0.7 vs. 8.5 +/- 0.3 (P<0.05) and 6.8 +/- 0.7 nmol/mg protein]. In comparison with N, the level of ubiquitin conjugates in the coronary artery, as assessed by immunoblotting, increased by 42% in HC but not in HC+VIT and was localized predominantly to media vascular smooth muscle cells by immunostaining. There was no difference in proteasome proteolytic activity among the study groups. These results demonstrate that the UPS is functionally active in early atherogenesis despite increase in oxidative stress with important repercussions in the pathophysiology and therapy of cardiovascular diseases.

Animals↗

PubMed2003

Mechanisms of renal structural alterations in combined hypercholesterolemia and renal artery stenosis.

OBJECTIVE: Atherosclerotic renovascular disease (ARVD) aggravates renal scarring more than other causes of renal artery stenosis (RAS), but the underlying pathogenic mechanisms of this potential profibrotic effect remain unclear. We tested the hypothesis that coexistence of atherosclerosis and RAS interferes with renal tissue remodeling. METHODS AND RESULTS: Single-kidney hemodynamics and function were quantified in vivo with electron-beam computed tomography in 3 groups of pigs (n=7 each): normal pigs, pigs 12 weeks after induction of unilateral RAS (RAS group), and pigs with similar-degree RAS fed a 12-week 2% hypercholesterolemic diet (HC+RAS, simulating early ARVD). Kidneys were studied ex vivo by Western blotting and immunohistochemistry. Renal volume, renal blood flow, and glomerular filtration rate were similarly decreased in RAS and HC+RAS ischemic kidneys, accompanied by similar increased expression of profibrotic factors like transforming growth factor-beta, tissue inhibitor of metalloproteinase-1, and plasminogen activator inhibitor-1. Nevertheless, HC+RAS kidneys showed increased intrarenal fibrosis compared with RAS-only kidneys. Furthermore, expression of nuclear factor-kappaB was increased, expression of extracellular (matrix metalloproteinase-2) and intracellular (ubiquitin) protein degradation systems was decreased, and apoptosis was blunted. CONCLUSIONS: Diet-induced HC superimposed on RAS accelerates the development of fibrosis in the stenotic kidney by amplifying profibrotic mechanisms and disrupting tissue remodeling. These alterations might contribute to renal disease progression in ARVD and might account for the increased propensity for end-stage renal disease.

Animals↗

PubMed2003

Hypertension exacerbates the effect of hypercholesterolemia on the myocardial microvasculature.

OBJECTIVE: Hypercholesterolemia (HC) and hypertension (HT) are both major risk factors for the development and progression of atherosclerotic heart disease, and their co-existence has been associated with an increased incidence of cardiac events in clinical studies. HC and HT are individually associated with abnormal myocardial vascular function, but whether HT exacerbates the HC-induced myocardial vascular dysfunction remains unclear. METHODS: We studied in pigs the effect of renovascular HT superimposed on diet-induced HC (HC+HT) on myocardial perfusion and microvascular permeability in vivo (using electron-beam computed tomography) in response to cardiac challenge (i.v. adenosine and dobutamine). The involvement of systemic and myocardial tissue oxidative stress in vitro was assessed by oxidizability of LDL, levels of endogenous antioxidants, and tissue activities of radical-scavenger systems. RESULTS: While in normal animals myocardial perfusion increased in response to i.v. adenosine (+36+/-13%, P<0.05), in HC and HT alone the increase was blunted. In HC+HT myocardial perfusion response was further attenuated and significantly lower than normal, and myocardial vascular resistance failed to decrease (+7.6+/-8.8 vs. -21.0+/-5.8%, P=0.02 versus normal). HC+HT also showed blunted response to dobutamine, and augmented increases in microvascular permeability in vivo. These functional abnormalities were associated with increased systemic and myocardial tissue oxidative stress compared to HC or HT alone, and a synergistic decrease in endogenous antioxidant defenses in myocardial tissue. Furthermore, chronic antioxidant vitamin supplementation in combined HC and HT improved myocardial vascular responses. CONCLUSION: HT amplifies the HC-induced myocardial microvascular dysfunction in vivo and increased oxidative stress in vitro. These alterations may potentially play a role in the increased incidence of cardiac events observed when HC and HT co-exist.

Adenosine↗

PubMed2003

Hypercholesterolemia and hypertension have synergistic deleterious effects on coronary endothelial function.

OBJECTIVE: Coronary endothelial dysfunction is associated with an increase in cardiac events. Hypercholesterolemia (HC) and hypertension (HT) are both associated with endothelial dysfunction, and their coexistence is associated with an increased incidence of cardiac events in epidemiological studies. However, pathogenic mechanisms are poorly understood. Here we studied the effects of coexisting HC and HT on coronary endothelial function. METHODS AND RESULTS: Four groups of pigs were studied after 12 weeks of a normal diet (n=9), a 2% HC diet (n=9), HT (achieved by unilateral renal artery stenosis, n=8), or HC+HT (n=6). Coronary endothelial function was tested, in epicardial arteries and arterioles, by using organ chamber techniques. Oxidative stress was measured in coronary artery tissue. Vasodilatory response to bradykinin and calcium ionophore was significantly impaired in animals with HC+HT compared with each risk factor alone (P<0.05 for both). In animals with coexistent HC and HT, the increase in oxidative stress was more pronounced compared with each risk factor alone (P<0.05). Furthermore, chronic antioxidant supplementation significantly improved coronary artery vasoreactivity. CONCLUSIONS: These results suggest that HC and HT have a synergistic deleterious effect on coronary endothelial function, associated with increased oxidative stress. This interaction may contribute to the increased incidence of coronary heart disease and cardiac events seen when HC and HT coexist.

Animals↗