The comparison of the relaxant effects of two methoxylated flavones in rat aortic rings.
The vascular effect of salvigenin (6-hydroxyapigenin 6,7,4' -trimethyl ether), a natural flavone, was investigated in comparison with another flavone, 6-hydroxyluteolin 6,7,3',4' -tetramethyl ether in rat aortic rings. Cumulative addition of their increasing concentrations (10(-9)-10(-4)M) produced graded relaxations on rings precontracted with noradrenaline (10(-6) M) and KCl (40 mM). The maximal relaxations induced by flavones were similar, however, based on their pEC50 values salvigenin displayed a higher potency than 6-hydroxyluteolin 6,7,3',4'-tetramethyl ether. Endothelium removal markedly reduced the relaxations to salvigenin while the responses to 6-hydroxyluteolin 6,7,3',4'-tetramethyl ether were partially affected. In addition, a significant decrease was observed in maximal responsiveness and sensitivity to flavones in the presence of L-NOARG, a NO synthase inhibitor. The cyclooxygenase inhibitor indomethacin significantly inhibited the relaxations to salvigenin, but not altered the responses to 6-hydroxyluteolin 6,7,3',4'-tetramethyl ether. Our results provide evidence that salvigenin is an effective flavone in causing vasorelaxation which appears to be mediated by endothelium derived NO and prostacyclin. Whereas, the other flavone, 6-hydroxyluteolin 6,7,3',4'-tetramethyl ether induced relaxant responses are partially endothelium, presumably NO mediated.
Uydeş-Doğan
B Sönmez
BS
Department of Pharmacology, Faculty of Pharmacy, Istanbul University, 34116, Beyazit, Istanbul, Turkey. sudogan@tr.net
Takir
Selçuk
S
Ozdemir
Osman
O
Kolak
Ufuk
U
Topçu
Gülaçti
G
Ulubelen
Ayhan
A
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047309:Flavones / Q000494:pharmacology*; D066298:In Vitro Techniques; D047311:Luteolin / Q000494:pharmacology; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors; D019335:Nitroarginine / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014665:Vasodilator Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D047309:Flavones; D014665:Vasodilator Agents; D009599:Nitroprusside; C057617:6-hydroxyluteolin; C014049:salvigenin; D019335:Nitroarginine; D052250:Nitric Oxide Synthase Type III; D047311:Luteolin; D000109:Acetylcholine; D011188:Potassium; D009638:Norepinephrine