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Research: CHEN and colleagues, C
Listed in Issue 78
Abstract
CHEN and colleagues, Clinical Research Institute of Montreal, University of Montreal, Montreal, Quebec, Canada, investigated whether vitamins C and E influenced vascular structure and function in hypertension by modulating activity of NADPH oxidase and superoxide dismutase (SOD).
Background
Ascorbic acid (vitamin C) and alpha-tocopherol (vitamin E) have antioxidant properties that could improve redox-sensitive vascular changes associated with hypertension.
Methodology
Adult, stroke-prone, spontaneously hypertensive rats (SHRSP) were divided into three groups: control (C; n=6); vitamin C-treated (vit C, 1000 mg/day; n=7); and vitamin E-treated (vit E, 1000 IU/day; n=8). All groups were fed 4% NaCl. Blood pressure (BP) was measured weekly. After 6 weeks of treatment, mesenteric arteries were analysed. Vascular O2- generation and NADPH oxidase activity were measured by chemiluminescence. Vascular SOD activity and plasma total antioxidant status (TAS) were determined by spectrophotometry.
Results
BP increased from 2127 to 2656 mm Hg in controls. Treatment prevented progression of hypertension (vit C, 2226 to 23414 mm Hg; vit E, 2209 to 22710 mm Hg). Acetylcholine-induced vasodilation was improved (p<0.05), and media-to-lumen ratio was reduced (p<0.05) in the treated group. O2– was lower in vitamin-treated groups compared with controls (vit C, 104 nmol/min/g dry tissue weight; vit E, 9.63.5 nmol/min/g dry tissue weight; C, 219 nmol/min/g dry tissue weight; p<0.05). Both vitamin-treated groups showed significant improvement in TAS (p<0.01). These effects were associated with decreased activation of vascular NADPH oxidase (vit C, 4610, vit E, 50, C, 7016 nmol/min/g dry tissue weight; p<0.05) and increased activation of SOD (vit C, 122, vit E, 81, C, 4.61 U/mg; p<0.05).
Conclusion
The results demonstrated that vitamins C and E reduced oxidative stress, improved vascular structure and function and prevented progression of hypertension in SHRSP. The authors concluded that the observed effects might be mediated via modulation of enzyme systems that generate free radicals.
References
Chen X et al. Antioxidant effects of vitamins C and E are associated with altered activation of vascular NADPH oxidase and superoxide dismutase in stroke-prone SHR. Hypertension 38 (3 Pt 2): 606-11. Sep 2001.