Atropine- and scopolamine-resistant subtypes of muscarinic receptors in the rabbit aorta.

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Manjeet S, Sim MK

Atropine- and scopolamine-resistant subtypes of muscarinic receptors in the rabbit aorta.

Eur J Pharmacol. 1989 Dec 12;174(1):99-105.

PubMed ID

2612581 [ View in PubMed

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Abstract

Tritiated acetylcholine ([3H]ACh) binds specifically to different muscarinic binding sites in the rabbit aorta. The binding of [3H]ACh to endothelial membranes was displacable by nanomolar concentrations of scopolamine but only by micromolar concentrations of atropine and homatropine. The reverse was true for smooth muscle membranes, i.e. [3H]ACh binding was displacable by nanomolar concentrations of atropine and homatropine but only by micromolar concentrations of scopolamine. Pirenzepine, AF-DX 116 and 4-diphenyl-acetoxy-N-methylpiperidine methobromide (4-DAMP) displaced the binding of [3H]ACh from both tissues in the nano- to micromolar range. Our findings indicate that endothelial receptors are characterised by a high affinity for scopolamine, which possesses a scopine base, and that muscle binding sites have a high affinity for antagonists possessing a tropine base (atropine, homatropine). Both the endothelial and smooth muscle binding sites have a low affinity for AF-DX 116, indicating that they are not of the cardiac type.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Homatropine methylbromide	Muscarinic acetylcholine receptor M2	Protein	Humans	Yes	Antagonist	Details