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Veterinary research communications2000; 23(1); 41-51; doi: 10.1023/a:1006154905374

Beta-adrenoceptors in equine trachea and heart.

Abstract: The density and subtype pattern of beta-adrenoceptors in equine tracheal epithelium, tracheal smooth muscle and heart from 6-9 horses were investigated by radioligand binding studies using the nonselective beta-adrenoceptor antagonist 125I-cyanopindolol (ICYP). The specific binding of ICYP was 341 +/- 162 fmol/mg protein (mean +/- SD) for epithelium, 42 +/- 13 fmol/mg for smooth muscle and 124 +/- 39 and 101+/- 19 fmol/mg for the cardiac atrium and ventricle, respectively. The Kd value of ICYP was 6.7 10.2 pmol/L. In competition studies, different concentrations of either the beta2-selective drug ICI 118551 or the beta1-selective CGP 20712A competed with 25 pmol/L ICYP for the binding sites. The competition curves for tracheal smooth muscle and epithelium were monophasic with an approximate Kd value for ICI 118551 of 1 nmol/L and for CGP 20712A of 10000 nmol/L. This corresponds to known Kd values for these substances binding to beta2-adrenoceptors. beta2-Adrenoceptors were also found in the heart, most pronounced in the atrium, where the density was 29% +/- 6% (mean +/- SD) of the total receptor density. CGP 20712A and ICI 118551 bound to the dominating binding site of beta1-adrenoceptors in the heart with Kd values of approximately I nmol/L and 100 nmol/L, respectively.
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Publication Date: 2000-07-25 PubMed ID: 10905817DOI: 10.1023/a:1006154905374Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research examines the density and subtype pattern of beta-adrenoceptors in the tracheal epithelium, tracheal smooth muscle, and heart of horses. Using radioligand binding studies, it demonstrates their existence in all examined areas with particular concentration in the cardiac atrium and gives us knowledge about the structure of the equine respiratory and cardiac system that can contribute to medical treatments.

Study Method

  • The researchers carried out binding studies with radioligands, using the nonselective beta-adrenoceptor antagonist 125I-cyanopindolol (ICYP). This is a commonly used technique to investigate receptor binding and was performed on samples harvested from the tracheal epithelium, tracheal smooth muscle, and heart of 6-9 horses.
  • ICYP binding gives the density of beta-adrenoceptors in these tissues.
  • To subtype the beta-adrenoceptors, they performed competition studies with beta2-selective drug ICI 118551 and the beta1-selective CGP 20712A. These drugs compete with ICYP for beta-adrenoceptor binding sites, with different affinities reflecting the subtype of the beta-adrenoceptor.

Results

  • They determined that specific ICYP binding was highest in the epithelium of the trachea, followed by cardiac atrium and ventricle, with the lowest value found in the tracheal smooth muscle. This means the highest number of beta-adrenoceptors in equine tissues was found in the tracheal epithelium.
  • Competition studies with beta2-selective ICI 118551 showed a strong affinity for the binding sites in tracheal smooth muscle and epithelium, showing these tissues to be rich in beta2-adrenoceptors.
  • However, the competition studies revealed the presence of beta2-adrenoceptors in the heart, with the most significant density in the atrium. Such a finding expands our understanding of the distribution of these receptors in the equine heart.
  • The heart had the highest affinity with beta1-selective CGP 20712A. This high affinity suggests a high density of beta1-adrenoceptors, particularly in the heart.

Conclusions

  • This study provides valuable information about beta-adrenoceptor density and subtype distributions in the trachea and heart tissues of horses, which, in turn, can contribute to understanding better how to medically treat illnesses involving these tissues, especially respiratory and cardiovascular conditions.

Cite This Article

APA
Töneke K. (2000). Beta-adrenoceptors in equine trachea and heart. Vet Res Commun, 23(1), 41-51. https://doi.org/10.1023/a:1006154905374

Publication

Veterinary research communications
ISSN: 0165-7380
NlmUniqueID: 8100520
Country: Switzerland
Language: English
Volume: 23
Issue: 1
Pages: 41-51

Researcher Affiliations

Töneke, K
  • Swedish University of Agricultural Sciences, Faculty of Veterinary Medicine, Department of Pharmnacology and Toxicology, Uppsala.

MeSH Terms

  • Adrenergic beta-Antagonists / metabolism
  • Animals
  • Binding, Competitive
  • Female
  • Heart Atria / metabolism
  • Heart Ventricles / metabolism
  • Horses / metabolism
  • Imidazoles / metabolism
  • Iodine Radioisotopes
  • Ligands
  • Male
  • Muscle, Smooth / metabolism
  • Myocardium / metabolism
  • Pindolol / analogs & derivatives
  • Pindolol / metabolism
  • Propanolamines / metabolism
  • Receptors, Adrenergic, beta / metabolism
  • Regression Analysis
  • Spectrometry, Gamma / veterinary
  • Trachea / metabolism

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Citations

This article has been cited 3 times.
  1. Witkowska-Piłaszewicz O, Pingwara R, Szczepaniak J, Winnicka A. The Effect of the Clenbuterol-β2-Adrenergic Receptor Agonist on the Peripheral Blood Mononuclear Cells Proliferation, Phenotype, Functions, and Reactive Oxygen Species Production in Race Horses In Vitro. Cells 2021 Apr 17;10(4).
    doi: 10.3390/cells10040936pubmed: 33920705google scholar: lookup
  2. Casoni D, Spadavecchia C, Adami C. Cardiovascular changes after administration of aerosolized salbutamol in horses: five cases. Acta Vet Scand 2014 Aug 14;56(1):49.
    doi: 10.1186/s13028-014-0049-zpubmed: 25124268google scholar: lookup
  3. Törneke K, Ingvast-Larsson C, Boström A, Appelgren LE. Muscarinic receptors in equine airways. Vet Res Commun 2002 Dec;26(8):637-50.
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