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Oroxylin A induces relaxation of porcine basilar arteries via cGMP pathway
Author(s) -
Tsai Andy PoYi,
Chen MeiFang,
Wang MeiJen,
Lee Tony JerFu
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.999.3
Subject(s) - myograph , chemistry , potassium channel , cyclic guanosine monophosphate , basilar artery , cerebral arteries , charybdotoxin , electrical impedance myography , medicine , vasodilation , endocrinology , pharmacology , nitric oxide
The possible involvement of cyclic guanosine monophosphate (cGMP) and potassium channels in mediating oroxylin A (Oro‐A)‐induced relaxation of porcine isolated basilar arteries was examined. Oro‐A, a flavonoid isolated from the natural herb, Scutellariae baicalensis, is used widely for various diseases. Its role in regulating cerebral vascular functions, however, remains unclear. Results from blood vessel myography studies indicated that Oro‐A in a concentration‐dependent manner relaxed U46619 (a thromboxane A2‐receptor agonist)‐contracted basilar arterial rings. The relaxations, which were independent of the endothelial cells and perivascular nerve fibers, were inhibited by blockers for nonspecific potassium channels, preferential calcium‐activated potassium (BKca)‐channels, and preferential ATP‐sensitive potassium (K ATP )‐channel. Also, Oro‐A‐induced vasorelaxation was drastically decreased in arteries pre‐contracted by high potassium. By using two‐electrode voltage clamp, Oro‐A, however, did not directly open the BKca‐ or K ATP ‐channels on oocytes from Xenopus leavis. Moreover, Oro‐A‐induced vasorelaxation was blocked by a soluble guanylate cyclase (sGC) inhibitor, but was not affected by inhibitors of adenylate cyclase or protein kinase A. In addition, concentrations of cGMP but not cAMP in endothelium‐denuded basilar arteries were significantly increased following incubation with Oro‐A. These results suggest that OroA increases synthesis of cGMP which then opens the BKca‐ and K ATP ‐channels on the smooth muscle cells of the basilar arteries causing relaxation. Together with its reported anti‐inflammatory effects, Oro‐A may be a promising compound for ameliorating cerebral neurovascular dysfunctions. Support or Funding Information Supported by Ministry of Science and Technology of Taiwan, Tzu Chi Foundation, and Tzu Chi University