Potentiating effects on contractions by purified baicalin and baicalein in the rat mesenteric artery

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)263-269
Journal / PublicationJournal of Cardiovascular Pharmacology
Issue number2
Publication statusPublished - Aug 2000
Externally publishedYes


The effects of purified baicalin and baicalein from the traditional Chinese herb, Huangqin, on contractions induced by phenylephrine, U46619, and high extracellular K+ were investigated in isolated rat mesenteric arteries. Both baicalin (1-100 μM) and baicalein (1-50 μM) potentiated the contractile response to phenylephrine in a concentration-related manner. Both flavonoids (10 μM) also enhanced the U46619- or 40 mM K+-induced contractions. Baicalein (100-300 μM) reduced the phenylephrine-induced tone. Prazosin at 1 μM did not affect U46619-induced contraction in the absence and presence of baicalein or baicalin. Neither baicalin (1-100 μM) nor baicalein (1-100 μM) affected the basal tension. Removal of the functional endothelium abolished the potentiating effects of baicalin and baicalein in arteries preconstricted by both constrictors. Pretreatment of endothelium-intact rings with 100 μMNG-nitro-L-arginine also potentiated phenylephrine- or U46619-induced contraction but completely inhibited the effects of baicalin and baicalein. Pretreatment with 1 mM L-arginine reversed the enhancing effect of baicalin but not of baicalein on phenylephrine-evoked contraction. Pretreatment with 10 μM baicalin or 10 μM baicalein significantly reduced the endothelium-dependent relaxation induced by acetylcholine or ionomycin. These results indicate that both baicalin and baicalein potentiated the evoked contractile response, likely through inhibition of nitric oxide formation and/or release in the endothelium.

Research Area(s)

  • Baicalein, Baicalin, Contraction, Endothelium, Mesenteric artery, Nitric oxide, Rat