title: Expression and function of protease-activated receptor 4 in human myometrium.
abstract: OBJECTIVE
  Little is known about the presence or functional effects of protease-activated receptor subtypes in human uterine tissues. The aims of this study were as follows: (1) to investigate for protease-activated receptor-4 messenger RNA and protein expression in human myometrium, (2) to evaluate the effects of a specific protease-activated receptor-4 activating peptide (AYPGKF-NH2) on spontaneous human myometrial contractility in vitro, and (3) to examine the effects of a protease-activated receptor-4 antagonist (tcYPGKF-NH2) on thrombin-mediated uterine contractility.
  
  
  METHODS
  Reverse transcriptase-polymerase chain reaction and Immunofluorescence studies were used to investigate for protease-activated receptor-4 messenger RNA and protein expression, respectively. Isometric tension recordings were used to examine the functional effects on contractility.
  
  
  RESULTS
  Reverse transcriptase-polymerase chain reaction demonstrated messenger RNA expression for protease-activated receptor-4 in pregnant and non-pregnant myometrium. Immunofluorescence confocal microscopy demonstrated the presence of protease-activated receptor-4 protein in myometrial cells. With the use of isometric recordings, protease-activated receptor 4-activating peptide elicited a stimulatory effect on spontaneous human pregnant myometrial contractility (13.1% +/- 2.7 SEM; n = 6; P < .05). Protease-activated receptor-4 antagonism alone elicited a significant uterorelaxant effect (14.7% +/- 2.4; n = 6; P < .05). The observed thrombin-mediated uterotonic effect was similar in the absence (46.1% +/- 12.8; n = 6) and presence (48.8% +/- 12.6; n = 6) of the protease-activated receptor-4 antagonist (P = .91).
  
  
  CONCLUSIONS
  This study outlines protease-activated receptor-4 messenger RNA and protein expression in human myometrium. Protease-activated receptor-4 activation exerts a mild uterotonic effect, whereas protease-activated receptor-4 antagonism results in a mild uterorelaxant effect. The potent human uterotonic effect of thrombin is not apparently mediated to any great extent by protease-activated receptor-4.
authors.affiliation: Department of Obstetrics and Gynecology, National University of Ireland Galway and the Clinical Science Institute, University College Hospital Galway, Galway, Ireland.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Allen
authors.forename: Margaret
authors.initials: M
authors.lastname: O'Brien
authors.forename: Anne M
authors.initials: AM
authors.lastname: Friel
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Smith
authors.forename: John J
authors.initials: JJ
authors.lastname: Morrison
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D009215:Myometrium / Q000502:physiology*; D009842:Oligopeptides / Q000096:biosynthesis / Q000502:physiology*; D011247:Pregnancy; D044462:Receptors, Proteinase-Activated / Q000096:biosynthesis* / Q000502:physiology; D014590:Uterine Contraction / Q000502:physiology*
chemical_list: C482003:AYPGKG-NH(2); D009842:Oligopeptides; D044462:Receptors, Proteinase-Activated