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Journal of Animal Science Abstract - Animal Physiology

β2– and β3–adrenergic receptors stimulation relaxes porcine myometrium in the peri-implantation period12


This article in JAS

  1. Vol. 94 No. 11, p. 4611-4618
    Received: Apr 26, 2016
    Accepted: Aug 28, 2016
    Published: October 27, 2016

    3 Corresponding author(s):

  1. W. Markiewicz 3a and
  2. J. J. Jaroszewskia
  1. a Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, 10-718 Olsztyn, Poland


These studies were to demonstrate whether the β3–receptor is involved in regulating the contractility of the swine myometrium in the peri-implantation period and to compare a relaxing activity of selective β2– and β3–adrenergic agonists (salbutamol and BRL 37344, respectively). Myometrial strips were collected form the gilts (n = 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 (10–9 to 10–5 M) with and without β-adrenergic receptor antagonists: butoxamine, propranolol, and bupranolol at 10–4 M. Moreover, the –log EC50 (pD2) of the agonists were compared. Following the incubation of myometrial strips with salbutamol and BRL 37344, a significant (P < 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 10–8 to 10–5 M, whereas BRL 37344 induced them at 10–7 to 10–5 M. Salbutamol exerted a significantly (P < 0.001) more potent reduction of the tension (pD2 = 6.98 ± 0.93 [SD]) than BRL 37344 (pD2 = 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 β3–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 β2–adrenergic receptor.

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