title: Potentiation of the uterus-relaxing effects of β-adrenergic agonists with nifedipine: studies on rats and the human myometrium.
abstract: OBJECTIVE
  We investigated how progesterone and salmeterol modify the effect of nifedipine in an in vivo preterm birth model in rats, and how terbutaline and nifedipine modify the contractions of the isolated human myometrium.
  
  
  METHODS
  Experimental animal and human myometrial studies.
  
  
  METHODS
  Twenty-four female Sprague-Dawley rats and 13 human uterine tissues sampled from cesarean section.
  
  
  METHODS
  Preterm birth was induced in Sprague-Dawley rats with a combination of mifepristone and prostaglandin-E(2). The animals were treated with nifedipine or its combination with salmeterol and progesterone. Additionally, isolated human myometrial strips from cesarean sections were stimulated with oxytocin, and the inhibitory effects of nifedipine and terbutaline were studied.
  
  
  RESULTS
  Nifedipine delayed the preterm delivery in the rats, but its effect was tripled by the addition of β(2)-mimetics, or abolished after progesterone pretreatment. Synergism was observed in the relaxing effects of nifedipine and terbutaline on the isolated human myometrium.
  
  
  CONCLUSIONS
  The action of nifedipine in delaying labor is impeded by progesterone. A combination of nifedipine and β(2)-agonists should be considered for the treatment or prevention of preterm birth.
authors.affiliation: Department of Pharmacodynamics and Biopharmacy, Faculty of Pharmacy, University of Szeged, Szeged, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Hajagos-Tóth
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Kormányos
authors.forename: George
authors.initials: G
authors.lastname: Falkay
authors.forename: Attila
authors.initials: A
authors.lastname: Pál
authors.forename: Róbert
authors.initials: R
authors.lastname: Gáspár
mesh_terms: D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000420:Albuterol / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D015735:Mifepristone / Q000008:administration & dosage / Q000494:pharmacology; D023421:Models, Animal; D009215:Myometrium / Q000187:drug effects; D009543:Nifedipine / Q000008:administration & dosage* / Q000494:pharmacology*; D010120:Oxytocics / Q000008:administration & dosage / Q000494:pharmacology; D011247:Pregnancy; D047928:Premature Birth / Q000517:prevention & control*; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D000068299:Salmeterol Xinafoate; D015145:Tocolysis / Q000379:methods; D015149:Tocolytic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D014590:Uterine Contraction / Q000187:drug effects*
chemical_list: D000318:Adrenergic beta-Agonists; D010120:Oxytocics; D015149:Tocolytic Agents; D015735:Mifepristone; D011374:Progesterone; D000068299:Salmeterol Xinafoate; D009543:Nifedipine; D000420:Albuterol