Pharmacological and ionic characterizations of the muscarinic receptors modulating [3H]acetylcholine release from rat cortical synaptosomes.

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Meyer EM, Otero DH

Pharmacological and ionic characterizations of the muscarinic receptors modulating [3H]acetylcholine release from rat cortical synaptosomes.

J Neurosci. 1985 May;5(5):1202-7.

PubMed ID

3998816 [ View in PubMed

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Abstract

The muscarinic receptors that modulate acetylcholine release from rat cortical synaptosomes were characterized with respect to sensitivity to drugs that act selectively at M1 or M2 receptor subtypes, as well as to changes in ionic strength and membrane potential. The modulatory receptors appear to be of the M2 type, since they are activated by carbachol, acetylcholine, methacholine, oxotremorine, and bethanechol, but not by pilocarpine, and are blocked by atropine, scopolamine, and gallamine (at high concentrations), but not by pirenzepine or dicyclomine. The ED50S for carbachol, acetylcholine, and oxotremorine are less than 10 microM, suggesting that the high affinity state of the receptor is functional. High ionic strength induced by raising the NaCl concentration has no effect on agonist (oxotremorine) potency, but increases the efficacy of this compound, which disagrees with receptor-binding studies. On the other hand, depolarization with either KCl or with veratridine (20 microM) reduces agonist potencies by approximately an order of magnitude, suggesting a potential mechanism for receptor regulation.

DrugBank Data that Cites this Article

Drugs

Methacholine

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Methacholine	Muscarinic acetylcholine receptor M1	Protein	Humans	Unknown	Agonist	Details