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Home / Equine Research Bank / Vet Res Commun / Muscarinic receptors in equine airways.
Veterinary research communications2003; 26(8); 637-650; doi: 10.1023/a:1020924921676

Muscarinic receptors in equine airways.

Abstract: The distribution of muscarinic receptors in equine airways was investigated using autoradiography. Frozen sections of tissue from six different levels in the bronchial tree, from the trachea to the distal bronchioles, were incubated in vitro with 1.5 nmol/L of the muscarinic receptor antagonist 1-[N-methyl-3H]scopolamine methyl chloride (3H-NMS). In addition, the subtype pattern of muscarinic receptors was investigated in equine tracheal smooth muscle using radioligand binding with methoctramine, tripinamidc, 4-DAMP-methiodide and pirenzipine as competitors against the binding of 1.3 nmol/L 3H-NMS. The autoradiograms showed specific labelling indicating a high density of muscarinic receptors in smooth-muscle tissue in all levels of the airway tree investigated. Besides muscle tissue, subepithelial glands were the only structures specifically labelled. The dominating subtypes in tracheal smooth muscle investigated with radioligand binding studies were found to be M2 and M4, as both methoctramine (pKd = 8.5) and tripinamide (pKd = 8.6 and 6.7 for two different sites) showed high affinity. The density of the M3-muscarinic receptor subtype was low, but this subtype could be detected with statistical significance when methoctramine was used as the competitor against 3H-NMS binding.
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Publication Date: 2003-01-01 PubMed ID: 12507038DOI: 10.1023/a:1020924921676Google Scholar: Lookup
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  • Journal Article
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  • 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.

The study explores the presence and types of muscarinic receptors in the airways of horses, and finds that they are primarily located in smooth muscle tissues and subepithelial glands, with a high density across all levels of the airway tree examined in the study.

Distribution of Muscarinic Receptors

  • The focus of the study is primarily on the distribution of muscarinic receptors in the equine (horse) respiratory system. Muscarinic receptors are proteins that play a considerable role in the function of the nervous system by acting as the main end points for the neurotransmitter acetylcholine.
  • The researchers sought to confirm these receptors’ specific locations, focusing on six different points in the bronchial tree, from the trachea to the distal bronchioles. They used a method called autoradiography, where they labelled the receptors with a radioactive compound, in this case, 3H-NMS; a muscarinic receptor antagonist, to visualize their distribution in the tissues.
  • The study revealed a high density of these muscarinic receptors in the smooth muscle tissue, across all levels of the bronchial tree investigated. In addition to the smooth muscle tissue, subepithelial glands were the only other structures specifically labelled, suggesting a high level of these receptors present in these areas.

Subtype Pattern of Muscarinic Receptors

  • The researchers further delved into the subtype patterns of these muscarinic receptors in the equine tracheal smooth muscle. They used a method called radioligand binding, using several competitors (methoctramine, tripinamidc, 4-DAMP-methiodide, pirenzipine) against the binding of another dose of 3H-NMS. This method is commonly employed to investigate the presence of receptors in a given tissue.
  • This process helps understand which specific types, or subtypes, of muscarinic receptors are present. In the smooth muscle of the horse’s trachea, the predominant subtypes found were M2 and M4. These were verified by the high affinity shown by both methoctramine and tripinamide, suggesting these particular types are dominant in this area.
  • Though the M3-muscarinic receptor subtype was discovered to be present in relatively low density, these receptors were significantly detectable when methoctramine was used as a competitor. These results may have implications in understanding more about the role of these different receptor subtypes within the horse’s respiratory system.

Cite This Article

APA
Törneke K, Ingvast-Larsson C, Boström A, Appelgren LE. (2003). Muscarinic receptors in equine airways. Vet Res Commun, 26(8), 637-650. https://doi.org/10.1023/a:1020924921676

Publication

Veterinary research communications
ISSN: 0165-7380
NlmUniqueID: 8100520
Country: Switzerland
Language: English
Volume: 26
Issue: 8
Pages: 637-650

Researcher Affiliations

Törneke, K
  • Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences, BMC, Box 573, SE-751 23 Uppsala, Sweden.
Ingvast-Larsson, C
    Boström, A
      Appelgren, L E

        MeSH Terms

        • Animals
        • Autoradiography / veterinary
        • Binding, Competitive
        • Bronchi / metabolism
        • Female
        • Horses / metabolism
        • In Vitro Techniques
        • Kinetics
        • Male
        • Muscarinic Antagonists / pharmacology
        • Muscle, Smooth / metabolism
        • N-Methylscopolamine / antagonists & inhibitors
        • N-Methylscopolamine / metabolism
        • Receptors, Muscarinic / classification
        • Receptors, Muscarinic / metabolism
        • Trachea / metabolism

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        Citations

        This article has been cited 2 times.
        1. Abraham G, Kottke C, Ammer H, Dhein S, Ungemach FR. Segment-dependent expression of muscarinic acetylcholine receptors and G-protein coupling in the equine respiratory tract.. Vet Res Commun 2007 Feb;31(2):207-26.
          doi: 10.1007/s11259-006-3396-zpubmed: 17180451google scholar: lookup
        2. Mazzone SB, Mori N, Burman M, Palovich M, Belmonte KE, Canning BJ. Fluorescent styryl dyes FM1-43 and FM2-10 are muscarinic receptor antagonists: intravital visualization of receptor occupancy.. J Physiol 2006 Aug 15;575(Pt 1):23-35.
          doi: 10.1113/jphysiol.2006.106351pubmed: 16728454google scholar: lookup
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