Antihypertensive effects of the flavonoid quercetin in spontaneously hypertensive rats

1 The effects of an oral daily dose (10 bg kg(-1)) of the flavonoid quercet in for 5 weeks in spontaneously hypertensive (SHR) and normotensive Wistar Kyoto rats (WKY) were analysed. 2 Quercetin induced a significant reduction in systolic (-18%), diastolic ( -23%) and mean (-21%) arterial blood pressure and heart rate (-12%) in SHR but not in WKY rats. 3 The left ventricular weight index and the kidney weight index in vehicle- treated SHR were significantly greater than in control WKY and these parame ters were significantly reduced in quercetin-treated SHR in parallel with t he reduction in systolic blood pressure. 4 Quercetin had no effect on the vasodilator responses to sodium nitropruss ide or to the vasoconstrictor responses to noradrenaline or KCI but enhance d the endothelium-dependent relaxation to acetylcholine (E-max = 58 +/- 5% vs 78 +/- 5%, P < 0.01) in isolated aortae. 5 The 24 h urinary isoprostane F-2<alpha> excretion and the plasma malonyld ialdehyde (MDA) levels in SHR rats were increased as compared to WKY rats. However, in quercetin-treated SHR rats both parameters were similar to thos e of vehicle-treated WKY. 6 These data demonstrate that quercetin reduces the elevated blood pressure , the cardiac and renal hypertrophy and the functional vascular changes in SHR rats without effect on WKY. These effects were associated with a reduce d oxidant status due to the antioxidant properties of the drug.