Mechanisms Involved in the Vasodilator Effect of the Flavanol Floranol in Rat Small Mesenteric Arteries

Abstract

The mechanism underlying the vasodilator effect of the flavonoid floranol was studied in rat small mesenteric arteries. Floranol produced a concentration-dependent vasorelaxant effect in endothelium-containing and endothelium-denuded vessels pre-contracted with phenylephrine, which was more potent in endothelium-intact vessels. In endothelium-intact mesenteric arteries, l-NAME but not indomethacin produced a shift to the right in the vasorelaxant effect of floranol. In endothelium-denuded vessels TEA and BaCl₂ did not change the floranol-induced vasorelaxation. When endothelium-denuded vessels were pre-contracted with 50 mM KCl, floranol induced a vasorelaxant effect comparable with phenylephrine pre-contracted vessels. We conclude that floranol is a new vasodilator compound in rat small mesenteric arteries. Part of this effect is dependent on endothelial nitric oxide (NO) and part is dependent on the inhibition of voltage-dependent calcium channels in the smooth muscle cells.

References

• 1 Knekt P, Jarvinen R, Reunanen A, Maatela J. Flavonoid intake and coronary mortality in Finland: a cohort study.  Br Med J. 1996;  312 478-81
• 2 Rice-Evans C, Miller N J, Paganga G. Antioxidant properties of phenolic compounds.  Trends Plant Sci. 1997;  2 152-9
• 3 Seigneur M, Bonnet J, Dorian B, Benchimol D, Drouillet F, Gouverneur G. et al . Effect of the consumption of alcohol, white wine, and red wine on platelets function and serum lipids.  J Appl Cardiol. 1990;  5 215-22
• 4 Herrera M D, Zarzuelo A, Jiménez J, Marhuenda E, Duarte J. Effects of flavonoids on rat aortic smooth muscle contractility: structure-activity relationships.  Gen Pharmacol. 1996;  27 273-7
• 5 Lemos V S, Santos M H, Rabelo L A, Cortes S F. Total assignments ¹H and ¹³C NMR spectra of a new prenylated flavononol from Dioclea grandiflora .  Magn Reson Chem. 2002;  40 793-4
• 6 Almeida A P, Cortes S F, Ferreira A J, Lemos V S. Increase on the coronary flow induced by dioclein in isolated rat heart.  Life Sci. 2002;  70 1121-8
• 7 Cortes S F, Rezende B A, Corriu C, Medeiros I, Teixeira M M, Lopes J M, Lemos V S. Pharmacological evidence for the activation of potassium channels as the mechanism involved in the hypotensive and relaxant effect of dioclein in rat small resistance arteries.  Br J Pharmacol. 2001;  133 849-58
• 8 Lemos V S, Freitas M R, Muller B, Lino Y D, Queiroga C EG, Cortes S F. Dioclein, a new nitric oxide- and endothelium-dependent vasodilator flavonoid.  Eur J Pharmacol. 1999;  386 41-6
• 9 Bhattacharyya J, Batista J S, Almeida R N. Dioclein, a flavanone from the roots of Dioclea grandiflora .  Phytochemistry. 1995;  38 277-8
• 10 Summanen J, Vuorela P, Rauha J P, Tammela P, Marjamaki K, Pasternack M. et al . Effects of simple aromatic compounds and flavonoids on Ca²⁺ fluxes in rat pituitary GH(4)C(1) cells.  Eur J Pharmacol. 2001;  414 125-33
• 11 Karaki H, Ozaki H, Hori M, Mitsui-Saito M, Amano K I, Harada K I. et al . Calcium movements, distribution, and functions in smooth muscle.  Pharmacol Rev. 1997;  49 157-230
• 12 Baker E H. Ion channels and the control of blood pressure.  Br J Clin Pharmacol. 2000;  49 185-98