PT  - JOURNAL ARTICLE
AU  - E. C. HULME
AU  - N. J. M. BIRDSALL
AU  - A. S. V. BURGEN
AU  - P. MEHTA
TI  - The Binding of Antagonists to Brain Muscarinic Receptors
DP  - 1978 Sep 01
TA  - Molecular Pharmacology
PG  - 737--750
VI  - 14
IP  - 5
4099  - http://molpharm.aspetjournals.org/content/14/5/737.short
4100  - http://molpharm.aspetjournals.org/content/14/5/737.full
SO  - Mol Pharmacol1978 Sep 01; 14
AB  - The equilibrium binding of muscarinic antagonists to a crude synaptosome fraction from rat cerebral cortex obeys the simple Langmuir isotherm. The affinity constants measured range from 105 to 1010 M-1 and in all cases agree within a factor of 3 with the corresponding values derived from measurements of anticholinergic potency on smooth muscle. The methodology which must be applied to obtain valid measurements of affinity constants from in vitro studies using radiolabelled ligands is discussed. ACKNOWLEDGMENTS The authors wish to express their thanks to Dr. R. B. Barlow for measurement of the antimuscarinic potency of PrBCh, and for the gift of the following compounds: N-methyl-piperidin-3-yl-phenylacetate methiodide; N-methyl-piperidin-4-yl-phenylacetate methiodide; N-methyl-piperidin-4-yl-diphenylacetate methiodide; N-methyl-quinuclidin-3-yl-phenylacetate; N-methyl-quinuclidin-3-yl-diphenylacetate.