title: Honokiol attenuates vascular contraction through the inhibition of the RhoA/Rho-kinase signalling pathway in rat aortic rings.
abstract: OBJECTIVE
  Honokiol is a small-molecule polyphenol isolated from the species Magnolia obovata. We hypothesized that honokiol attenuated vascular contractions through the inhibition of the RhoA/Rho-kinase signalling pathway.
  
  
  METHODS
  Rat aortic rings were denuded of endothelium, mounted in organ baths, and subjected to contraction or relaxation. Phosphorylation of 20kDa myosin light chains (MLC(20) ), myosin phosphatase targeting subunit 1 (MYPT1) and protein kinase C (PKC)-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase (MLCP) of 17kDa (CPI17) were examined by immunoblot. We also measured the amount of guanosine triphosphate RhoA as a marker for RhoA activation.
  
  
  RESULTS
  Pretreatment with honokiol dose-dependently inhibited the concentration-response curves in response to sodium fluoride (NaF) or thromboxane A(2) agonist U46619. Honokiol decreased the phosphorylation levels of MLC(20) , MYPT1(Thr855) and CPI17(Thr38) as well as the activation of RhoA induced by 8.0mm NaF or 30nm U46619.
  
  
  CONCLUSIONS
  These results demonstrated that honokiol attenuated vascular contraction through the inhibition of the RhoA/Rho-kinase signalling pathway.
authors.affiliation: Cardiovascular Research Institute, Kyungpook National University School of Medicine, Daegu, Republic of Korea.
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Seok
authors.forename: Hae Joung
authors.initials: HJ
authors.lastname: Cho
authors.forename: Byung-Yoon
authors.initials: BY
authors.lastname: Cha
authors.forename: Je-Tae
authors.initials: JT
authors.lastname: Woo
authors.forename: In Kyeom
authors.initials: IK
authors.lastname: Kim
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D001011:Aorta / Q000187:drug effects; D001713:Biphenyl Compounds / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D017705:Lignans / Q000494:pharmacology*; D031566:Magnolia / Q000737:chemistry*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D018994:Myosin Light Chains / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D011728:Pyridones; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D012969:Sodium Fluoride; D014661:Vasoconstriction / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors*; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors*; D000498:Allyl Compounds; D010636:Phenols
chemical_list: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D001713:Biphenyl Compounds; D017705:Lignans; D018994:Myosin Light Chains; D043263:Myosin-Light-Chain Phosphatase; D010936:Plant Extracts; D011728:Pyridones; D012969:Sodium Fluoride; D014665:Vasodilator Agents; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; C105928:CP 117; C005499:honokiol; D000498:Allyl Compounds; D010636:Phenols