title: Proteinase-activated receptor-2 activating peptides: distinct canine coronary artery receptor systems.
abstract: In canine coronary artery preparations, the proteinase-activated receptor-2 (PAR(2)) activating peptides (PAR(2)-APs) SLIGRL-NH(2) and 2-furoyl-LIGRLO-NH(2) caused both an endothelium-dependent relaxation and an endothelium-independent contraction. Relaxation was caused at peptide concentrations 10-fold lower than those causing a contractile response. Although trans-cinnamoyl-LIGRLO-NH(2), like other PAR(2)-APs, caused relaxation, it was inactive as a contractile agonist and instead antagonized the contractile response to SLIGRL-NH(2). RT-PCR-based sequencing of canine PAR(2) revealed a cleavage/activation (indicated by underlines) sequence (SKGR/SLIGKTDSSLQITGKG) that is very similar to the human PAR(2) sequence (R/SLIGKV). As a synthetic peptide, the canine PAR-AP (SLIGKT-NH(2)) was a much less potent agonist than either SLIGRL-NH(2) or 2-furoyl-LIGRLO-NH(2), either in the coronary contractile assay or in a Madin-Darby canine kidney (MDCK) cell PAR(2) calcium signaling assay. In the MDCK signaling assay, the order of potencies was as follows: 2-furoyl-LIGRLO-NH(2) >> SLIGRL-NH(2) = trans-cinnamoyl-LIGRLO-NH(2) >> SLIGKT-NH(2), as expected for PAR(2) responses. In the coronary contractile assay, however, the order of potencies was very different: SLIGRL-NH(2) >> 2-furoyl-LIGRLO-NH(2) >> SLIGKT-NH(2), trans-cinnamoyl-LIGRLO-NH(2) = antagonist. Because of 1) the distinct agonist (relaxant) and antagonist (contractile) activity of trans-cinnamoyl-LIGRLO-NH(2) in the canine coronary contractile assays, 2) the different concentration ranges over which the peptides caused either relaxation or contraction in the same coronary preparation, and 3) the markedly distinct structure-activity profiles for the PAR-APs in the coronary contractile assay, compared with those for PAR(2)-mediated MDCK cell calcium signaling, we suggest that the canine coronary tissue possesses a receptor system for the PAR-APs that is distinct from PAR(2) itself.
authors.affiliation: Department of Pharmacology & Therapeutics, University of Calgary Faculty of Medicine, 3330 Hospital Drive N.W., Calgary, Alberta, Canada.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Saifeddine
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Seymour
authors.forename: Yu-Pei
authors.initials: YP
authors.lastname: Xiao
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Compton
authors.forename: Steeve
authors.initials: S
authors.lastname: Houle
authors.forename: Rithwik
authors.initials: R
authors.lastname: Ramachandran
authors.forename: Wallace K
authors.initials: WK
authors.lastname: MacNaughton
authors.forename: Serge
authors.initials: S
authors.lastname: Simonet
authors.forename: Christine
authors.initials: C
authors.lastname: Vayssettes-Courchay
authors.forename: Tony J
authors.initials: TJ
authors.lastname: Verbeuren
authors.forename: Morley D
authors.initials: MD
authors.lastname: Hollenberg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D002460:Cell Line; D003331:Coronary Vessels / Q000187:drug effects* / Q000378:metabolism; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D007213:Indomethacin / Q000494:pharmacology; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D044463:Receptor, PAR-1 / Q000819:agonists / Q000378:metabolism; D044464:Receptor, PAR-2 / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D018040:Receptors, Neurokinin-1 / Q000378:metabolism; D013045:Species Specificity; D013329:Structure-Activity Relationship; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000737:chemistry / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000737:chemistry / Q000494:pharmacology*; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: C487404:2-furoyl-LIGRLO-amide; D009842:Oligopeptides; C462999:PAR-1-activating peptide; D012333:RNA, Messenger; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D018040:Receptors, Neurokinin-1; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C113425:cinnamoyl-LIGRLO-amide; C112356:seryl-leucyl-isoleucyl-glycyl--arginyl-leucinamide; D019061:src-Family Kinases; D007213:Indomethacin