Vasorelaxant effects of icariin on isolated canine coronary artery.
Owing to its cardiovascular therapeutical effects, icariin, a flavonoid isolated from Epimedii herba, is considered to be the major active constituent of Epimedii herba. The aim of this study is to investigate the effect of icariin on precontracted coronary artery isolated from canine. Coronary artery segments were isolated from normal anesthetized Beagle dogs and cut into 5-mm rings. The rings were mounted in an organ chamber and contracted by either 40 mM KCl or 10 microM PGF2alpha, and vasorelaxant tone to icariin was measured. Treatment of icariin could significantly produce a relaxation of precontracted coronary arterial rings with intact endothelium in a concentration-dependent manner. Comparatively, the vasorelaxation disappeared in denuded-endothelium rings. Furthermore, the vasorelaxant effect of icariin was blocked by Nomega-Nitro- L-arginine Methyl Ester (L-NAME), 1H-[1, 2, 4]-oxadiazolo [4, 3-a] quinoxalin-1-one (ODQ) but not by indomethacin and glibenclamide, respectively. Tetraethylammonium (TEA) could partly antagonize the vasorelaxant effect triggered by icariin. There was no significant gene expression difference of the endothelial nitric oxide synthase (eNOS) gene in coronary arterial rings among the different concentrations of icariin by RT-PCR, but the activity of eNOS was increased in a concentration-dependent manner after icariin exposure. These results suggest that icariin produces NO-dependent relaxation in the isolated canine coronary artery, and the possible mechanism is involved in the activation of eNOS protein and NO-cGMP pathway.
Xu
Hai-Bin
HB
Department of Cardiology, the Affiliated Hospital of Zhejiang Traditional Chinese Medicine University, Hangzhou, China.
Huang
Zhao-Quan
ZQ
D000704:Analysis of Variance; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects* / Q000201:enzymology / Q000503:physiopathology; D015237:Dinoprost / Q000494:pharmacology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005419:Flavonoids / Q000494:pharmacology*; D005905:Glyburide / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D023421:Models, Animal; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D010069:Oxadiazoles / Q000494:pharmacology; D010120:Oxytocics / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019789:Tetraethylammonium / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects* / Q000235:genetics
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D000889:Anti-Arrhythmia Agents; D004365:Drugs, Chinese Herbal; D004791:Enzyme Inhibitors; D005419:Flavonoids; D010069:Oxadiazoles; D010120:Oxytocics; D026902:Potassium Channel Blockers; D011810:Quinoxalines; D012333:RNA, Messenger; D019789:Tetraethylammonium; D015237:Dinoprost; D052250:Nitric Oxide Synthase Type III; D005905:Glyburide; D019331:NG-Nitroarginine Methyl Ester; C056599:icariin; D007213:Indomethacin