title: Proteinase-activated receptor-2-mediated relaxation in mouse tracheal and bronchial smooth muscle: signal transduction mechanisms and distinct agonist sensitivity.
abstract: We characterized the tracheal and bronchial relaxation caused by proteinase-activated receptor-2 (PAR-2) activation in ddY mice and/or in wild-type and PAR-2-knockout mice of C57BL/6 background. Ser-Leu-Ile-Gly-Arg-Leu-amide (SLIGRL-NH(2)) and Thr-Phe-Leu-Leu-Arg-amide, PAR-2- and PAR-1-activating peptides, respectively, caused relaxation in the isolated ddY mouse trachea and main bronchus. The relaxation was abolished by specific inhibitors of cyclooxygenase (COX)-1, COX-2, mitogen-activated protein kinase kinase (MEK), and p38 MAP kinase. The MEK and p38 MAP kinase inhibitors did not affect prostaglandin E(2)-induced relaxation. Inhibitors of cytosolic Ca(2+)-dependent phospholipase A(2) (PLA), Ca(2+)-independent PLA(2), diacylglycerol lipase, tyrosine kinase, and protein kinase C exhibited no or only minor inhibitory effects on the PAR-mediated relaxation. Trypsin, a PAR-2 activator, and 2-furoyl-Leu-Ile-Gly-Arg-Leu-amide, a potent PAR-2-activating peptide, in addition to SLIGRL-NH(2), caused airway relaxation in wild-type C57BL/6 mice, as in ddY mice. In PAR-2-knockout mice, the peptide effects were absent and the potency of trypsin decreased. Desensitization of PAR-2 and/or PAR-1 greatly suppressed the relaxant effect of trypsin. The bronchial and tracheal tissues displayed distinct sensitivities toward trypsin and the PAR-2-activating peptides. Our data indicate an involvement of both COX-1 and COX-2, and the MEK-extracellular signal-regulated kinase and p38 MAP kinase signaling pathways in the PAR-2- and PAR-1-triggered relaxation of mouse airway tissue, and substantiate a role for PAR-2 in regulating both the trachea and bronchial responsiveness in the mouse lung.
authors.affiliation: Division of Physiology and Pathophysiology, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan. kawabata@phar.kindai.ac.jp
authors.forename: Atsufumi
authors.initials: A
authors.lastname: Kawabata
authors.forename: Satoko
authors.initials: S
authors.lastname: Kubo
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ishiki
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kawao
authors.forename: Fumiko
authors.initials: F
authors.lastname: Sekiguchi
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Kuroda
authors.forename: Morley D
authors.initials: MD
authors.lastname: Hollenberg
authors.forename: Toru
authors.initials: T
authors.lastname: Kanke
authors.forename: Naohiro
authors.initials: N
authors.lastname: Saito
mesh_terms: D000818:Animals; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D007527:Isoenzymes / Q000378:metabolism; D008071:Lipoprotein Lipase / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D018345:Mice, Knockout; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth; D010455:Peptides / Q000494:pharmacology; D010741:Phospholipases A / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D044463:Receptor, PAR-1 / Q000502:physiology; D044464:Receptor, PAR-2 / Q000502:physiology*; D015398:Signal Transduction; D014132:Trachea; D014357:Trypsin / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D008565:Membrane Proteins; D010455:Peptides; D044463:Receptor, PAR-1; D044464:Receptor, PAR-2; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D048051:p38 Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; D010741:Phospholipases A; D008071:Lipoprotein Lipase; D014357:Trypsin; D015232:Dinoprostone