Evidence that PAR-1 and PAR-2 mediate prostanoid-dependent contraction in isolated guinea-pig gallbladder.
We have investigated the ability of protease-activated receptor-1 (PAR-1), PAR-2, PAR-3 and PAR-4 agonists to induce contractile responses in isolated guinea-pig gallbladder. Thrombin, trypsin, mouse PAR-1 activating (SFLLRN-NH(2)) peptide, and mouse PAR-2 activating (SLIGRL-NH(2)) and human PAR-2 activating (SLIGKV-NH(2)) peptides produced a concentration-dependent contractile response. Mouse PAR-4 activating (GYPGKF-NH(2)) peptide, the mouse PAR-1 reverse (NRLLFS-NH(2)) peptide, the mouse PAR-2 reverse (LRGILS-NH(2)) and human PAR-2 reverse (VKGILS-NH(2)) peptides caused negligible contractile responses at the highest concentrations tested. An additive effect was observed following the contractile response induced by either trypsin or thrombin, with the addition of a different PAR agonist (SFLLRN-NH(2) and SLIGRL-NH(2), respectively). Desensitization to PAR-2 activating peptide attenuated the response to trypsin but failed to attenuate the response to PAR-1 agonists, and conversely desensitization to PAR-1 attenuated the response to thrombin but failed to alter contractile responses to PAR-2 agonists. The contractile responses produced by thrombin, trypsin, SFLLRN-NH(2) and SLIGRL-NH(2) were markedly reduced in the presence of the cyclo-oxygenase inhibitor, indomethacin, whilst the small contractile response produced by NRLLFS-NH(2) and LRGILS-NH(2) were insensitive to indomethacin. The contractile responses to thrombin, trypsin, SFLLRN-NH(2) and SLIGRL-NH(2) were unaffected by the presence of: the non-selective muscarinic antagonist, atropine; the nitric oxide synthase inhibitor, L-NAME; the sodium channel blocker, tetrodotoxin; the combination of selective tachykinin NK(1) and NK(2) receptor antagonists, (S)-1-[2-[3-(3,4-dichlorphenyl)-1 (3-isopropoxyphenylacetyl) piperidin-3-yl] ethyl]-4-phenyl-1 azaniabicyclo [2.2.2] octane chloride (SR140333) and (S)-N-methyl-N-[4-acetylamino-4-phenylpiperidino-2-(3, 4-dichlorophenyl)-butyl] benzamide (SR48968), respectively. The results indicate that PAR-1 and PAR-2 activation causes contractile responses in the guinea-pig gallbladder, an effect that is mediated principally by prostanoid release, and is independent of neural mechanisms.
Tognetto
M
M
Department of Experimental & Clinical Medicine, Pharmacology Unit, University of Ferrara, Via Fossato di Mortara 19, 44100 Ferrara, Italy.
Trevisani
M
M
Maggiore
B
B
Navarra
G
G
Turini
A
A
Guerrini
R
R
Bunnett
N W
NW
Geppetti
P
P
Harrison
S
S
D000818:Animals; D029742:Caenorhabditis elegans Proteins; D004305:Dose-Response Relationship, Drug; D005704:Gallbladder / Q000187:drug effects / Q000502:physiology*; D006168:Guinea Pigs; D015801:Helminth Proteins / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D011453:Prostaglandins / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D013373:Substance P / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology
D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D011453:Prostaglandins; C087977:par-2 protein, C elegans; D013373:Substance P; D017346:Protein Serine-Threonine Kinases; D013917:Thrombin; D007213:Indomethacin