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Vol 82, No 12 (2011)
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Differences in the effects of β2- and β3-adrenoceptor agonists on spontaneous contractions of human nonpregnant myometrium

Anna Pedzińska-Betiuk, Beata Modzelewska, Marcin Jóźwik, Maciej Jóźwik, Anna Kostrzewska
Ginekol Pol 2011;82(12).

open access

Vol 82, No 12 (2011)
ARTICLES

Abstract

Abstract Objective: This study aimed to compare the relaxant properties of BRL 37344 with β2-adrenoceptors agonist ritodrine on the contractility of human nonpregnant myometrium. Material and methods: The activity of myometrial strips mounted in an organ bath was recorded under isometric conditions using force transducers with digital output. Contractility before and after cumulative additions of both uterorelaxants and with preincubation with β-adrenoceptor antagonists bupranolol, propranolol, and butoxamine were studied. Results: Both BRL 37344 (10-10 – 10-4 mol/L) and ritodrine (10-10 – 10-5 mol/L) decreased the area under curve, or AUC, value (logIC50 -6.45 ± 0.18 and -8.71 ± 0.35, respectively), and the degree of inhibition of spontaneous contractile activity was similar (< 30%). However, BRL 37344 decreased the mean frequency of contractions, whereas ritodrine decreased the mean amplitude of contractions. The inhibition of contractions by BRL 37344 was partially antagonized by bupranolol and propranolol, but not with butoxamine. The inhibition by ritodrine was counteracted by all these antagonists. Conclusions: The effects of BRL37344 and ritodrine on human nonpregnant myometrium are quantitatively similar in respect to the inhibition of spontaneous contractility, yet are also distinct due to their substantially different influences on contraction parameters. Our data indicate that β3-adrenoceptor activation is not the sole effect of BRL 37344 on this tissue.

Abstract

Abstract Objective: This study aimed to compare the relaxant properties of BRL 37344 with β2-adrenoceptors agonist ritodrine on the contractility of human nonpregnant myometrium. Material and methods: The activity of myometrial strips mounted in an organ bath was recorded under isometric conditions using force transducers with digital output. Contractility before and after cumulative additions of both uterorelaxants and with preincubation with β-adrenoceptor antagonists bupranolol, propranolol, and butoxamine were studied. Results: Both BRL 37344 (10-10 – 10-4 mol/L) and ritodrine (10-10 – 10-5 mol/L) decreased the area under curve, or AUC, value (logIC50 -6.45 ± 0.18 and -8.71 ± 0.35, respectively), and the degree of inhibition of spontaneous contractile activity was similar (< 30%). However, BRL 37344 decreased the mean frequency of contractions, whereas ritodrine decreased the mean amplitude of contractions. The inhibition of contractions by BRL 37344 was partially antagonized by bupranolol and propranolol, but not with butoxamine. The inhibition by ritodrine was counteracted by all these antagonists. Conclusions: The effects of BRL37344 and ritodrine on human nonpregnant myometrium are quantitatively similar in respect to the inhibition of spontaneous contractility, yet are also distinct due to their substantially different influences on contraction parameters. Our data indicate that β3-adrenoceptor activation is not the sole effect of BRL 37344 on this tissue.
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Keywords

Adrenergic Agonists, BRL 37344, human, Myometrium, Ritodrine

About this article
Title

Differences in the effects of β2- and β3-adrenoceptor agonists on spontaneous contractions of human nonpregnant myometrium

Journal

Ginekologia Polska

Issue

Vol 82, No 12 (2011)

Bibliographic record

Ginekol Pol 2011;82(12).

Keywords

Adrenergic Agonists
BRL 37344
human
Myometrium
Ritodrine

Authors

Anna Pedzińska-Betiuk
Beata Modzelewska
Marcin Jóźwik
Maciej Jóźwik
Anna Kostrzewska

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