title: Rapid functional upregulation of vasocontractile endothelin ETB receptors in rat coronary arteries.
abstract: OBJECTIVE
  Endothelin ET(B) receptors mediate under normal physiological conditions vasorelaxation in coronary arteries. However, vasocontractile ET(B) receptors appear in coronary arteries of ischemic heart disease patients. Interestingly, organ culture of isolated coronary arteries also induces upregulation of vasocontractile ET(B) receptors. This study examines the early time course and mechanism behind upregulation of contractile ET(B) receptors in isolated rat coronary arteries during short-term organ culture.
  
  
  METHODS
  Coronary artery segments were mounted in wire-myographs and incubated in physiological saline solution. Contractions were measured after exposure to the specific ET(B) receptor agonist Sarafotoxin 6c (S6c) and the endogenous agonists endothelin-1 and endothelin-3. Protein localization and levels of ET(B) and phosphorylated-extracellular-signal-regulated-kinase-1/2 (ERK1/2) were examined by immunohistochemistry.
  
  
  RESULTS
  Fresh arteries showed negligible vasoconstriction to S6c. However, incubation for only 4 and 7h increased S6c contractions two- and seven-fold, respectively. Furthermore, 7h incubation enhanced vasocontractile responses to endothelin-3 and increased ET(B) receptor density in vascular smooth muscle cells. ERK1/2 was activated rapidly after start of incubation. Moreover, incubation with either the transcriptional inhibitor actinomycin D or the mitogen-activated-protein kinase kinase 1/2 (MEK1/2) inhibitor U0126 attenuated contractile ET(B) receptor upregulation. U0126 attenuated ET(B) receptor protein levels after 24 h of incubation.
  
  
  CONCLUSIONS
  Coronary arteries rapidly upregulate vasocontractile ET(B) receptors during organ culture via transcriptional mechanisms and MEK-ERK1/2 signalling. This model may mimic the mechanisms seen in ischemic conditions. Furthermore, these findings have important experimental implications in tissue bath experiments lasting for more than 4h.
authors.affiliation: Department of Clinical Experimental Research, Glostrup Research Institute, University of Copenhagen, Glostrup Hospital, Ndr. Ringvej 69, DK-2600 Glostrup, Copenhagen, Denmark. grfrsk01@regionh.dk
authors.forename: Gry Freja
authors.initials: GF
authors.lastname: Skovsted
authors.forename: Anne Fog
authors.initials: AF
authors.lastname: Pedersen
authors.forename: Rikke
authors.initials: R
authors.lastname: Larsen
authors.forename: Majid
authors.initials: M
authors.lastname: Sheykhzade
authors.forename: Lars
authors.initials: L
authors.lastname: Edvinsson
mesh_terms: D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D003331:Coronary Vessels / Q000187:drug effects* / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004195:Disease Models, Animal; D019332:Endothelin-1 / Q000378:metabolism; D019334:Endothelin-3 / Q000378:metabolism; D048369:MAP Kinase Kinase 1 / Q000378:metabolism; D048370:MAP Kinase Kinase 2 / Q000378:metabolism; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D017202:Myocardial Ischemia / Q000503:physiopathology; D009570:Nitriles / Q000494:pharmacology; D009924:Organ Culture Techniques; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D044023:Receptor, Endothelin B / Q000819:agonists / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014757:Viper Venoms / Q000494:pharmacology*
chemical_list: D002070:Butadienes; D019332:Endothelin-1; D019334:Endothelin-3; D009570:Nitriles; D044023:Receptor, Endothelin B; C113580:U 0126; D014662:Vasoconstrictor Agents; D014757:Viper Venoms; C057354:sarafotoxins s6; D003609:Dactinomycin; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2