Antioxidant Intervention Attenuates Myocardial Neovascularization in Hypercholesterolemia

Abstract

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)-1␣ and vascular endothelial growth factor (VEGF). Methods and Results-Three groups of pigs (nϭ6 each) were studied after 12 weeks of normal or 2% HC diet or HCϩantioxidant 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-1␣, nitrotyrosine, and superoxide dismutase (SOD) were determined in myocardial tissue. The HC and HCϩantioxidant groups had similar increases in serum cholesterol levels. HC animals showed an increase in subendocardial spatial density of microvessels compared with normal (160.5Ϯ11.8 versus 95.3Ϯ8.2 vessels/cm 2 , PϽ0.05), which was normalized in HCϩantioxidant (92.5Ϯ20.5 vessels/cm 2 , PϽ0.05 versus HC), as was arteriolar tortuosity. In addition, HC induced upregulation of VEGF, HIF-1␣, and nitrotyrosine expression and decreased SOD expression and activity, all of which were preserved by antioxidant intervention. Conclusions-Changes

Role of Oxidative Stress in Remodeling of the Myocardial Microcirculation in Hypertension

“…8 Briefly, microfil silicone rubber (MV-122, Flow Tech, Inc) was perfused through a cannulated left anterior descending coronary artery under physiological pressure until it flowed freely from the myocardial veins. Sectioned anterior wall myocardial samples were scanned at 0.49°increments, and images were digitized for reconstruction of 3D volume images.…”

“…Sectioned anterior wall myocardial samples were scanned at 0.49°increments, and images were digitized for reconstruction of 3D volume images. 8 Image analysis was performed using the Analyze software package (Biomedical Imaging Resource, Mayo Clinic). The myocardium was tomographically divided into 3 equal parts, and 7 slices obtained at equal intervals were analyzed in each third.…”

“…The angiogenic effects of VEGF are mediated largely by its receptor Flk-1 and facilitated by cell surface receptors like alpha(v)beta3 integrins, which are expressed on angiogenic vessels. 7 However, despite the redox sensitivity of VEGF expression, and the ability to improve microvascular architecture in other disease states like hypercholesterolemia, 8 the efficacy of chronic antioxidant intervention to attenuate myocardial microvascular remodeling in HT has not been fully explored.…”

“…9 We have previously demonstrated the feasibility of studying with -CT the 3D myocardial microvascular architecture and tortuousity, a unique marker that characterizes angiogenic vessels. 8 Therefore, this study was designed to test the hypotheses that in early HT coronary microvascular remodeling is driven by oxidative stress and would be attenuated during chronic antioxidant supplementation.…”

Effects of Proteasome Inhibition on the Kidney in Experimental Hypercholesterolemia

“…cDNA was synthesized using Invitrogen SuperScrip firststrand synthesis kit as we have recently described (23). To investigate the mRNA expression of prepro-ET-1, ET-A, and ET-B receptors, realtime PCR (DNA engine OPTICON; MJ Research, Waltham, MA) was performed using SYBR Green JumpStart TaqReadyMix kit (Sigma, St. Louis, MO).…”