title: In vitro vasorelaxation mechanisms of Isoapiole extracted from Lemonfragrant Angelica Root on rat thoracic aorta.
abstract: BACKGROUND
  Lemonfragrant Angelica (Ostericum citriodorum (Hance) C. Q. Yuan & Shan) is a traditional Chinese herb for treatment of angina pectoris, stomach pain and abdominal pain. However, its active components and mechanisms of action were not well understood.
  
  
  OBJECTIVE
  In this study, we investigated whether the isoapiole extracted from Lemonfragrant Angelica Root (LAR) could directly stimulate the production of nitric oxide (NO) in vascular endothelial cells (VECs) and lead to the vascular relaxation
  
  
  METHODS
  Vascular activity experiments were performed in aortic rings isolated from Wistar rats using standard muscle bath procedures. Isoapiole was added with different concentrations (0.75, 2.5, 5μg/mL), and vessel relaxation of rat aortic rings pre-contracted with norepinephrine (NE) or potassium chloride was recorded. NO release from aortic rings exposed to isoapiole (5μg/mL) was measured by Griess method. The endothelial nitric oxide synthase (eNOS) expression in primary human umbilical vein endothelial cells (HUVECs) incubated with isoapiole was determined using Western blot and microplate reader assay. Classical receptor antagonists, channel and enzymatic inhibitors were used to check the mechanisms involved.
  
  
  RESULTS
  Isoapiole (0.75, 2.5, 5μg/mL) inhibited norepinephrine-induced contraction in endothelium-intact rat aortic rings. However, a very weak relaxation of aortic rings was obtained in endothelium-denuded preparations. Isoapiole (0.75, 2.5, 5μg/mL) did not have vascular relaxative effect on neither endothelium-intact nor endothelium-denuded aortas pre-contracted with KCl (60mmol/L). The vasorelaxation effect of isoapiole on rat aortic rings was attenuated by the eNOS inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME). This result suggested that suggested that the isoapiole action was at least partially mediated by promoting eNOS expression. It was further found that isoapiole (5μg/mL) increased NO production in isolated rat thoracic aorta rings. Isoapiole increased eNOS expression leading to NO production in HUVECs.
  
  
  CONCLUSIONS
  Isoapiole stimulates NO production in the endothelium, leading to vascular dilatation.
authors.affiliation: Development & Research Center of New Chinese Drugs, School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, China. Electronic address: shansy6@163.com.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Yin
authors.affiliation: The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou 510000, China. Electronic address: 33119812@qq.com.
authors.forename: Shuangwei
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Development & Research Center of New Chinese Drugs, School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, China. Electronic address: 603861053@qq.com.
authors.forename: Guoyong
authors.initials: G
authors.lastname: Tong
authors.affiliation: Development & Research Center of New Chinese Drugs, School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, China. Electronic address: 1033617090@qq.com.
authors.forename: Lihong
authors.initials: L
authors.lastname: Deng
authors.affiliation: Development & Research Center of New Chinese Drugs, School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, China. Electronic address: 727978606@qq.com.
authors.forename: Tuliang
authors.initials: T
authors.lastname: Liang
authors.affiliation: Development & Research Center of New Chinese Drugs, School of Chinese Materia Medica, Guangzhou University of Chinese Medicine, Guangzhou 510006, China. Electronic address: zhjxsh@aliyun.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
mesh_terms: D029969:Angelica / Q000737:chemistry*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000302:isolation & purification / Q000494:pharmacology*; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D008517:Phytotherapy; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry*; D010946:Plants, Medicinal; D017208:Rats, Wistar; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D004365:Drugs, Chinese Herbal; D010936:Plant Extracts; D014665:Vasodilator Agents; C000617391:isoapiole; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III
keywords: ENOS; Endothelial cells; Isoapiole; Isoapiole (PubChem CID: 15559838); L-NAME (PubChem CID:39836); NO; Norepinephrine (PubChem CID:439260); Potassium chloride (PubChem CID:4873); Vasorelaxation