The experimental study of vascular relaxation induced by the ethanol extract of Blueberry(BE)

Abstract

Objective To study the effects and the mechanism of the ethanol extract of Blueberry(BE) on relaxation vascular endothelium or smooth muscle.Methods To use rat aorta as the specimen,to observe the effects of BE on induced relaxation of the phenylephrine-precontracted aorta.and approach the mechanism on vascular endothelium or smooth muscle.Results BE induced relaxation of the phenylephrine-precontracted(1.0×10~(-5)mol·L~(-1) aorta in a dose-dependent way(P<0.01),which was disappeared by removal of functional endothelium(P<0.01).Pretreatment of the aortic tissues with NG-nitro-L-arginine methyl ester(L-NAME),methylene blue,or 1H[1,2,4]-oxadiazole-[4,3_a]-quinoxalin-1-one (ODQ) inhibited the vascular relaxation induced by BE(P<0.01).BE-induced vascular relaxations were also markedly attenuated by addition of verapamil or diltiazem,while the relaxant effect of BE was not blocked by pretreatment with indomethacine,glibenclamide,tetraethylammonium(TEA),atropine,propranolol(P<0.01).Conclusion These results suggest that BE dilates vascular smooth muscle via endothelium-dependent nitricoxide-cGMP signaling pathway,possible involvement of L-type Ca~(2+) channel. Key words: Ethanol extract of blueberry; Vascular relaxation; Nitric oxide-cyclic guanosine monophosphate