Vitamin C lowers blood pressure and alters vascular responsiveness in salt-induced hypertension.
The present study was undertaken to investigate the effect of vitamin C treatment on blood pressure and vascular reactivity in salt-induced hypertension. Male Sprague-Dawley rats were fed a normal rat diet, a high-sodium (8% NaCl) diet, a normal rat diet plus vitamin C treament (100 mg x kg(-1) x day(-1)), or a high-sodium diet plus vitamin C treatment for 6 weeks. Salt loading significantly increased blood pressure, which was attenuated by vitamin C treatment. Aortic rings from the different groups were suspended for isometric-tension recording. The contractile response to noradrenaline was significantly increased in the salt-loaded rats. Vitamin C reduced the sensitivity of aortic rings to noradrenaline in rats on normal and high-sodium diets. In noradrenaline-precontracted rings, the relaxation response to acetylcholine, which was attenuated in the salt-loaded rats, was restored by vitamin C treatment. Pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME) abolished the enhanced response to acetylcholine caused by vitamin C. The results suggest that the antihypertensive effect of vitamin C is associated with a reduction in vascular sensitivity to noradrenaline and enhancement of endothelium-dependent relaxation due to increased nitric oxide bioavailability.
Ettarh
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Department of Physiology, College of Medicine, University of Lagos, PMB 12003, Idi-Araba, Lagos, Nigeria. ettarh@yahoo.com
Odigie
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IP
Adigun
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D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology* / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006973:Hypertension / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017673:Sodium Chloride, Dietary / Q000633:toxicity; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology
D017673:Sodium Chloride, Dietary; D001205:Ascorbic Acid