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Research article2002Peer reviewed

Muscarinic receptors in equine airways

Torneke, K; Ingvast-Larsson, C; Bostrom, A; Appelgren, LE

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-H-3]scopolamine methyl chloride (H-3-NMS). In addition, the subtype pattern of muscarinic receptors was investigated in equine tracheal smooth muscle using radioligand binding with methoctramine, tripinamide, 4-DAMP-methiodide and pirenzipine as competitors against the binding of 1.3 nmol/L H-3-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 M-2 and M-4, as both methoctramine (pK(d) = 8.5) and tripinamide (pK(d) = 8.6 and 6.7 for two different sites) showed high affinity. The density of the M-3-muscarinic receptor subtype was low, but this subtype could be detected with statistical significance when methoctramine was used as the competitor against H-3-NMS binding.

Keywords

antagonists; autoradiography; bronchi; bronchioles; horse; muscarinic receptors; trachea

Published in

Veterinary Research Communications
2002, Volume: 26, number: 8, pages: 637-650
Publisher: KLUWER ACADEMIC PUBL

      SLU Authors

    • Törneke, Karolina

      • Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences

      • Ingvast Larsson, Carina

        • Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences

        • Boström, Agneta

          • Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences

          • Appelgren, Lars-Erik

            • Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences

          UKÄ Subject classification

          Pathobiology

          Publication identifier

          DOI: https://doi.org/10.1023/A:1020924921676

          Permanent link to this page (URI)

          https://res.slu.se/id/publ/97416