Abstract
Chronic oral quercetin exerts antihypertensive effects in spontaneously hypertensive
rats (SHR). In the present study, the vasodilator effects of the flavonoid quercetin
and its main metabolite isorhamnetin were analysed in isolated thoracic aorta, iliac
artery and on the isolated perfused mesenteric resistance vascular bed from SHR and
normotensive Wistar Kyoto rats (WKY). In noradrenaline-precontracted vessels from
SHR there was an inverse correlation between the relaxant potency (pIC50 ) of quercetin (4.76 ± 0.02, 5.08 ± 0.12, 5.30 ± 0.18, in aorta, iliac arteries and
mesentery, respectively) and isorhamnetin (4.90 ± 0.11, 5.38 ± 0.15 and 5.80 ± 0.10,
respectively) and the diameter of the vessel studied. Both flavonoids were more potent
in endothelium-denuded aortae and iliac arteries from SHR than from normotensive WKY
rats. In addition, in aortae from SHR both flavonoids restored the endothelial-dependent
vasodilation. Isorhamnetin, but not quercetin, also reduced the endothelium-dependent
contractile responses induced by acetylcholine. These direct vasodilator effects,
together with the improvement of endothelial function, are good candidates to explain
the blood pressure reduction and vascular protective effects of quercetin in animal
models of hypertension and possibly in human cardiovascular diseases.
Abbreviations
pIC50 :Negative logarithm of the drug concentration which inhibited 50 % of the contractile
response
S.E.M.:Standard error fo the mean
SHR:Spontaneously hypertensive rats
WKY:Wistar Kyoto normotensive rats
Key words
Quercetin - flavonoid - isorhamnetin - SHR - resistance vessels
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Francisco Perez-Vizcaino
Departmento Farmacología
Facultad Medicina
Universidad Complutense
28040 Madrid
Spain
Fax: +34-913-941-470
Email: fperez@med.ucm.es