Proteinase-activated receptor-2 activation induces uterine contractility in term pregnant rats that is not dependent on mast cell activation and cyclo-oxygenase products

OBJECTIVES: This study was undertaken to evaluate the effect of proteinase-activated receptor-2 (PAR-2) activation on the contractility of uterine tissues from term pregnant rats and the role of mast cells and prostaglandins in such an effect. STUDY DESIGN: Uterine rings from pregnant (day 20-21) Sprague-Dawley rats were used for isometric tension recording in organ chamber experiments (Krebs solution, 5% carbon dioxide in air, 37 degrees C, pH approximately 7.4). Responses to the PAR-2 activating peptide SLIGRL (serine-leucine-isoleucine-glycine-arginine-leucine), and to the inactive reverse peptide LRGILS (leucine-arginine-glycine-isoleucine-leucine-serine) were determined after pretreatments with compound 48/80, cromolyn, S[+]-chlorpheniramine maleate, cimetidine, combinations of histamine (H) receptor antagonists with cromolyn or ibuprofen and compared with vehicle. RESULTS: SLIGRL significantly augmented contractility of uterine tissues, and this response was not inhibited by compound 48/80, cromolyn, and ibuprofen, as well as by H(1)- and H(2)-receptor antagonists, alone or in combination with cromolyn. CONCLUSION: PAR-2 activation augments uterine contractility in tissues obtained from term pregnant rats, and this effect is independent of mast cell activation or cyclo-oxygenase pathway products.