title: Endothelium-dependent contraction of rat thoracic aorta induced by gallic acid.
abstract: The vascular effect of a component of hydrolysable tannins, gallic acid, was examined in isolated rat thoracic aorta. Gallic acid exerted a contractile effect on the phenylephrine- or prostaglandin F(2/alpha)-precontracted endothelium-intact arteries. In endothelium-denuded arteries, the contractile response to-gallic acid was absent. Pretreatment with N(G)-nitro-L-arginine methyl ester (30 microM) abolished the gallic acid-induced contraction. Pretreatment with indomethacin (10 microM) or BQ610 (100 nM) had no observed effect. Pretreatment with gallic acid (1-10 microM) significantly attenuated the relaxation induced by acetylcholine, and that with 10 microM gallic acid also reduced the potency of sodium nitroprusside in the relaxation, without a reduction in efficacy, in endothelium-denuded arteries. These findings indicate that gallic acid induced endothelium-dependent contraction and strongly inhibited the endothelium-dependent relaxation rather than the endothelium-independent relaxation, probably through inhibition of endothelial nitric oxide (NO) production. Since NO plays an important role in vasodilative regulation and inflammatory disorders, these findings may also indicate that gallic acid interferes with the inflammatory responses.
authors.affiliation: Department of Medicine, Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa 920-1181, Japan. f-sanae@hokuriku-u.ac.jp
authors.forename: Fujiko
authors.initials: F
authors.lastname: Sanae
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Miyaichi
authors.forename: Hisao
authors.initials: H
authors.lastname: Hayashi
mesh_terms: D000109:Acetylcholine; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects; D005707:Gallic Acid / Q000494:pharmacology*; D008297:Male; D010656:Phenylephrine; D008517:Phytotherapy; D011453:Prostaglandins; D051381:Rats; D017208:Rats, Wistar; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D011453:Prostaglandins; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D005707:Gallic Acid; D000109:Acetylcholine