Abstract
In the present studies, we investigate the binding properties of [3H]quinuclidinyl benzilate ([3H]QNB) and [3H]N-methylscopolamine ([3H]NMS) to muscarinic acetylcholine receptors (mAChR) in rat brain homogenates. Our results indicate that the hydrophilic receptor ligand, [3H]NMS, is able to interact with high affinity only with a fraction of the receptor sites available to the lipophilic ligand, [3H]QNB. Furthermore, displacement experiments demonstrated that while both unlabeled QNB and NMS displaced [3H]NMS binding according to the law of mass-action, NMS, but not QNB, displayed binding heterogeneity when [3H]QNB was used as a ligand. Our data suggest that the lipid solubility of a particular mAChR ligand might play an important role in determining its profile of binding to the receptor.
Original language | English (US) |
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Pages (from-to) | 263-266 |
Number of pages | 4 |
Journal | European Journal of Pharmacology |
Volume | 110 |
Issue number | 2 |
DOIs | |
State | Published - Apr 2 1985 |
Externally published | Yes |
Bibliographical note
Funding Information:This research was supported in part by a UMAB graduate school research award, an NIH Biomedical Research Support grant 2-507-440S770-05 and a grant from the National Science Foundation (BNS-84-06357). The authors are grateful to Ms. Anita Saulsbury and Mrs. Pat Tretter for typing the manuscript, and to Mr. Michael Gentry for his invaluable technical assistance.
Keywords
- Muscarinic receptors
- Receptor heterogeneity
- [H]N-Methylscopolamine
- [H]Quinuclidinyl benzilate