Direct effects of quercetin on impaired reactivity of spontaneously hypertensive rat aortae: comparative study with ascorbic acid

Ajay, M.; Achike, F.I.; Mustafa, A.M.; Mustafa, M.R. (2006) Direct effects of quercetin on impaired reactivity of spontaneously hypertensive rat aortae: comparative study with ascorbic acid. Clinical and experimental pharmacology and physiology, 33 (4). pp. 345-350. ISSN 1440-1681

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    Abstract

    1. There is a growing interest in the anti-oxidant characteristics and use of flavonoids in the management of cardiovascular diseases. The cardiovascular mechanism of action of these plant derivatives remains controversial. This study compared the effects of the flavonoid quercetin with those of the anti-oxidant vitamin ascorbic acid (vitamin C) on the reactivity of aortic rings from spontaneously hypertensive rats (SHR). 2. The phenylephrine (PE)-induced contractile and the endothelium-dependent and independent relaxant responses of aortic rings from 21 to 22 week old SHR and age-matched normotensive Wistar (WKY) rats were observed in the presence of quercetin or ascorbic acid. All the experiments were performed in the presence of the cyclooxygenase inhibitor, indomethacin (10 mmol/L). 3. The endothelium-dependent and independent relaxations to acetylcholine (ACh) and sodium nitroprusside (SNP), respectively, were significantly lesser in the SHR compared to the WKY tissues whereas the contractile responses to PE were similar in both tissues. Pretreatment of WKY rings with quercetin or ascorbic acid had no effect on the responses to ACh or PE. In the SHR tissues, however, quercetin or ascorbic acid significantly improved the relaxation responses to ACh and reduced the contractions to PE with greater potency for quercetin. Both compounds lacked any effects on the responses to SNP in either aortic ring types. Nw-nitro-L-arginine methyl ester (L-NAME, 10 mmol/L) significantly attenuated the vasodepressor effects of quercetin and ascorbic acid, raising the responses to PE to a level similar to that observed in the control SHR tissues. In L-NAME pretreated aortic rings, quercetin and ascorbic acid inhibited the contractile responses to PE with the same magnitude in WKY and SHR tissues. 4. The present results suggest that acute exposure to quercetin improves endothelium-dependent relaxation and reduces the contractile responses of hypertensive aortae with a greater potency than ascorbic acid. This suggests a better vascular.

    Item Type: Article
    Creators:
    1. Ajay, M.
    2. Achike, F.I.
    3. Mustafa, A.M.
    4. Mustafa, M.R.
    Journal or Publication Title: Clinical and experimental pharmacology and physiology
    Additional Information: Correspondence: Dr Mohd Rais Mustafa, Department of Pharmacology, Faculty of Medicine, University of Malaya, Kuala Lumpur, 50603, Malaysia. Email: rais@um.edu.my
    Subjects: R Medicine > RM Therapeutics. Pharmacology
    Divisions: Faculty of Medicine
    Depositing User: Ms Haslinda Lahuddin
    Date Deposited: 09 Jan 2012 10:35
    Last Modified: 21 Oct 2014 13:01
    URI: http://eprints.um.edu.my/id/eprint/2405

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