Importance of NAD(P)H Oxidase–Mediated Oxidative Stress and Contractile Type Smooth Muscle Myosin Heavy Chain SM2 at the Early Stage of Atherosclerosis

Abstract

Background-Increased vascular oxidative stress induced by hyperlipidemia may alter the phenotype of vascular smooth muscle (SM) cells and play a crucial role in the progression of atherosclerosis. To clarify the mechanisms underlying vascular dysfunction and oxidative stress in hypercholesterolemia, we compared the effects of antioxidant probucol with those of pravastatin on aortic stiffness, phenotypic modulation, oxidative stress, and NAD(P)H oxidase essential subunit p22 phox expression in aortic medial SM cells of cholesterol-fed rabbits by using color image analysis of immunostained sections. Methods and Results-Japanese white male rabbits were fed either normal chow or 1% cholesterol diet for 14 weeks. After the first 7 weeks, cholesterol-fed rabbits were further divided into 3 groups: those fed with cholesterol feed only and those additionally given pravastatin (10 mg/d) or probucol (1.3 g/d) for the last 7 weeks. Within 7 weeks of treatment, probucol improved aortic stiffness more effectively than did pravastatin, inhibiting phenotypic modulation by selectively upregulating contractile-type SM myosin heavy chain isoform SM2 and by reducing both p22 phox and superoxide content in medial SM cells of cholesterol-fed rabbit aorta. No significant differences in cholesterol levels, superoxide content, and endothelial NO synthase levels in the intima, aortic morphology and fibrosis, and synthetic-type myosin heavy chain in medial SM cells were observed between the 2 drug-treated groups. Conclusions-These results suggest that oxidative stress and SM2 in medial SM cells might be important factors for vascular dysfunction, and strategies aimed at blocking NAD(P)H oxidase and upregulating SM2 may have therapeutic potential against the progression of atherosclerosis in hypercholesterolemia.

Comparative effects of pitavastatin and probucol on oxidative stress, Cu/Zn superoxide dismutase, PPAR-γ, and aortic stiffness in hypercholesterolemia

“…We measured minimum aortic dimension (D min; in mm), maximum aortic dimension during the ejection period (Dmax; in mm), and the systolic amplitude of the internal dimension (⌬D ϭ Dmax Ϫ Dmin). Stiffness parameter ␤ was calculated using the equation ␤ ϭ ln(BPs/BPd)/(⌬D/Dmin), where BPs is the maximum systolic aortic pressure and BPd is the minimum diastolic aortic pressure, as previously reported (22). This parameter ␤ represents a physiological stiffness index of the vessel independent of the operating level of aortic pressure.…”

“…Selective and quantitative analyses for aortic morphology and protein expression were performed as described previously (22). The sections were quantified morphometrically with a camera control program system (ACT-1, version 2.51) with a digital camera (DXM1200F, Nikon) connected to an automation microscope (Eclipse E1000, Nikon).…”

“…The sections were quantified morphometrically with a camera control program system (ACT-1, version 2.51) with a digital camera (DXM1200F, Nikon) connected to an automation microscope (Eclipse E1000, Nikon). In each aorta, the cross-sectional area, total cell number in the aortic media, and intima-to-media ratio were obtained as previously reported (22). The total fractional fibrosis of the media was determined by Sirius red staining, and the collagen volume fraction, which was representative of collagen including types I and III, was identified by using birefringency under polarized light illumination as previously reported (22).…”

Nifedipine Activates PPARγ and Exerts Antioxidative Action Through Cu/ZnSOD Independent of Blood-pressure Lowering in SHRSP

“…For in situ imaging of ROS, we incubated frozen sections (30 m) of rat heart tissues with fluorophores sensitive to ·O2 , DHE 10 mol/L 21) , or DCF-DA 10 µmol/L (Invitrogen Corporation, Carlsbad, CA), since H2O2 is also known to contribute to oxidative damage. Images of DHE and DCF were obtained with a laser scanning confocal microscope (LSM510; Carl Zeiss, Jena, Germany).…”

Hydrodynamic Studies on the Quaternary Structure of Recombinant Mouse Purβ

“…It has been hypothesized that strand-specific binding by Pur␣/Pur␤ to this element disrupts a core MCAT enhancer motif, thereby repressing SM␣A promoter activity in cultured fibroblasts and vascular smooth muscle cells (23). That Pur␣ and Pur␤ function as inhibitors of SM␣A expression is of particular interest due to the essential role played by SM␣A in vascular contraction (24), cell motility (25), wound repair (26), and arterial remodeling (27,28). Despite biochemical similarities, gain-of-function studies suggest that Pur␣ and Pur␤ are not redundant in terms of their transcriptional repressor activity toward the full-length mouse SM␣A promoter in transfected vascular smooth muscle cells (21,29).…”