title: β- and β-adrenergic receptors stimulation relaxes porcine myometrium in the peri-implantation period.
abstract: These studies were to demonstrate whether the β-receptor is involved in regulating the contractility of the swine myometrium in the peri-implantation period and to compare a relaxing activity of selective β- and β-adrenergic agonists (salbutamol and BRL 37344, respectively). Myometrial strips were collected form the gilts ( = 8) on d 12 to 14 of pregnancy. Changes in the contractility of myometrial strips were assessed further to the administration of increasing concentrations of the agonists (10 to 10 ) with and without β-adrenergic receptor antagonists: butoxamine, propranolol, and bupranolol at 10 . Moreover, the -log EC (pD) of the agonists were compared. Following the incubation of myometrial strips with salbutamol and BRL 37344, a significant ( < 0.05 to 0.001) reduction in the contractility, seen as decreased tension, amplitude, and frequency of contractions, as compared to the pretreatment period was noted, although salbutamol induced these changes at a concentration of 10 to 10 , whereas BRL 37344 induced them at 10 to 10 . Salbutamol exerted a significantly ( < 0.001) more potent reduction of the tension (pD = 6.98 ± 0.93 [SD]) than BRL 37344 (pD = 3.41 ± 0.1.61). The impact of salbutamol was neutralized by all administered antagonists, while a relaxing effect of BRL 37344 was completely inhibited by bupranolol and partially by propranolol. The data indicate that the β-adenergic receptor is involved in the regulation of smooth muscle contractility in the swine uterus in the peri-implantation period and its activation triggers relaxation of the myometrium to a lesser degree than the activation of the β-adrenergic receptor.
authors.forename: W
authors.initials: W
authors.lastname: Markiewicz
authors.forename: J J
authors.initials: JJ
authors.lastname: Jaroszewski
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000420:Albuterol / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D010064:Embryo Implantation / Q000502:physiology*; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D009215:Myometrium / Q000378:metabolism*; D011247:Pregnancy; D011943:Receptors, Adrenergic, beta; D013552:Swine / Q000502:physiology*; D014590:Uterine Contraction / Q000187:drug effects
chemical_list: D000318:Adrenergic beta-Agonists; D004983:Ethanolamines; D011943:Receptors, Adrenergic, beta; C057368:BRL 37344; D000420:Albuterol