High-affinity binding of [3H]acetylcholine to muscarinic cholinergic receptors.

Published

Journal Article

High-affinity binding of [3H]acetylcholine to muscarinic cholinergic sites in rat CNS and peripheral tissues was measured in the presence of cytisin, which occupies nicotinic cholinergic receptors. The muscarinic sites were characterized with regard to binding kinetics, pharmacology, anatomical distribution, and regulation by guanyl nucleotides. These binding sites have characteristics of high-affinity muscarinic cholinergic receptors with a Kd of approximately 30 nM. Most of the muscarinic agonist and antagonist drugs tested have high affinity for the [3H]acetylcholine binding site, but pirenzepine, an antagonist which is selective for M-1 receptors, has relatively low affinity. The ratio of high-affinity [3H]acetylcholine binding sites to total muscarinic binding sites labeled by [3H]quinuclidinyl benzilate varies from 9 to 90% in different tissues, with the highest ratios in the pons, medulla, and heart atrium. In the presence of guanyl nucleotides, [3H] acetylcholine binding is decreased, but the extent of decrease varies from 40 to 90% in different tissues, with the largest decreases being found in the pons, medulla, cerebellum, and heart atrium. The results indicate that [3H]acetylcholine binds to high-affinity M-1 and M-2 muscarinic receptors, and they suggest that most M-2 sites have high affinity for acetylcholine but that only a small fraction of M-1 sites have such high affinity.

Full Text

Duke Authors

Cited Authors

  • Kellar, KJ; Martino, AM; Hall, DP; Schwartz, RD; Taylor, RL

Published Date

  • June 1, 1985

Published In

Volume / Issue

  • 5 / 6

Start / End Page

  • 1577 - 1582

PubMed ID

  • 4009247

Pubmed Central ID

  • 4009247

International Standard Serial Number (ISSN)

  • 0270-6474

Language

  • eng

Conference Location

  • United States