title: Mechanisms of the dilator action of the Erigerontis Herba on rat aorta.
abstract: BACKGROUND
  Erigerontis Herba is widely used as a traditional Chinese medicine and is commonly used for neuroprotection and vascular protection.
  
  
  OBJECTIVE
  In this study, the vasodilator effects of Erigerontis Herba (DZXX) were investigated using rat isolated aorta rings.
  
  
  METHODS
  The involvement of endothelium in the vasorelaxation was studied by comparing response of endothelium-intact and endothelium-denuded aorta rings which precontracted with U46619. The involvement of K(+) channels was studied by pretreatment of the aorta rings with various K(+) channel inhibitors. The involvement of Ca(2+) channel was studied by incubating aorta rings with Ca(2+)-free solution, primed with U46619 prior to elicit contraction by addition of Ca(2+) solution.
  
  
  RESULTS
  DZXX (0.2-2mg/ml) induced a concentration-dependent relaxation on U44619-precontracted aorta rings with EC50 of 0.354±0.036mg/ml. Removal of endothelium or pretreatment with a BKCa inhibitor iberiotoxin, KIR inhibitor barium chloride or Kv inhibitor 4-aminopyridine produced no effect on the DZXX-induced vasorelaxation. However, pretreatment with a KATP inhibitor glibenclamide or a non-selective K(+) channel inhibitor tetraethylammonium produced significant inhibition on the DZXX-induced vasorelaxation by 29.9% and 21.3%, respectively. Pretreatment with DZXX (0.4, 1.2 and 2mg/ml) produced a concentration-dependent inhibition on Ca(2+)-induced vasoconstriction.
  
  
  CONCLUSIONS
  These results suggest that the vasodilator effect of DZXX was endothelium-independent, mediated by decreasing the influx of Ca(2+) by calcium channel inhibition and increasing the influx of K(+) by opening of a KATP channel.
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Chi-Man
authors.initials: CM
authors.lastname: Koon
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Subiyanto
authors.initials: S
authors.lastname: Fong
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Elaine
authors.initials: E
authors.lastname: Wat
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Wang
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: David
authors.initials: D
authors.lastname: Wing-Shing Cheung
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Clara
authors.initials: C
authors.lastname: Bik-San Lau
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
authors.forename: Ping-Chung
authors.initials: PC
authors.lastname: Leung
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
authors.forename: Han-Dong
authors.initials: HD
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
authors.forename: Qin-Shi
authors.initials: QS
authors.lastname: Zhao
authors.affiliation: Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong; The Chinese University of Hong Kong-Zhejiang University Joint Laboratory on Natural Products and Toxicology Research, Shatin, New Territories, Hong Kong. Electronic address: kpfung@cuhk.edu.hk.
authors.forename: Kwok-Pui
authors.initials: KP
authors.lastname: Fung
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D019659:Asteraceae; D002118:Calcium / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000502:physiology; D000431:Ethanol / Q000737:chemistry; D066298:In Vitro Techniques; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D012997:Solvents / Q000737:chemistry; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D010936:Plant Extracts; D026902:Potassium Channel Blockers; D012997:Solvents; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D000431:Ethanol; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D002118:Calcium
keywords: Aorta; Erigerontis Herba; Vasodilation