RT Journal Article
SR Electronic
T1 The Binding of Agonists to Brain Muscarinic Receptors
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 723
OP 736
VO 14
IS 5
A1 N. J. M. BIRDSALL
A1 A. S. V. BURGEN
A1 E. C. HULME
YR 1978
UL http://molpharm.aspetjournals.org/content/14/5/723.abstract
AB The interaction of agonists with muscarinic receptors has been investigated by measuring the binding of [3H]muscarinic agonists to membrane preparations from the rat cortex and by means of [3H]agonist/agonist and [3H]antagonist/agonist competition experiments. The binding data can be explained by the presence of two major populations of agonist binding sites which do not interconvert during the binding experiments and have the same affinity constants for antagonists. The ratio of the affinity constants of an agonist for the two sites can vary from 1 to about 275. There is quantitative agreement between the agonist affinity constants for the two sites and parameters derived from the action of muscarinic agonists on smooth muscle, A third (minor) population of "super-high" affinity agonist binding sites has been detected. ACKNOWLEDGMENTS The authors wish to thank P. Mehta and R. Edees for skilled technical assistance and Drs. C. R. Hiley and J. M. Young for their permission to include some of their unpublished results in Table 7.