Quantitative analysis of vasodilatory action of quercetin on intramural coronary resistance arteries of the rat in vitro.

BACKGROUND: Dietary quercetin improves cardiovascular health, relaxes some vascular smooth muscle and has been demonstrated to serve as a substrate for the cyclooxygenase enzyme. AIMS: 1. To test quantitatively a potential direct vasodilatory effect on intramural coronary resistance artery segments, in different concentrations. 2. To scale vasorelaxation at different intraluminal pressure loads on such vessels of different size. 3. To test the potential role of prostanoids in vasodilatation induced by quercetin. METHODS: Coronary arterioles (70-240 µm) were prepared from 24 rats and pressurized in PSS, using a pressure microangiometer. RESULTS: The spontaneous tone that developed at 50 mmHg was relaxed by quercetin in the 10(-9) moles/lit concentration (p<0.05), while 10(-5) moles/lit caused full relaxation. Significant relaxation was observed at all pressure levels (10-100 mmHg) at 10(-7) moles/lit concentration of quercetin. The cyclooxygenase blocker indomethacin (10(-5) moles/lit) induced no relaxation but contraction when physiological concentrations of quercetin were present in the tissue bath (p<0.02 with Anova), this contraction being more prominent in smaller vessels and in the higher pressure range (p