RT Journal Article
SR Electronic
T1 Muscarinic Sites in the Amphibian Central Nervous System: Characterization and Temperature Studies
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 141
OP 148
VO 17
IS 2
A1 RICHARD R. ALMON
A1 JOHN E. MARTNER
YR 1980
UL http://molpharm.aspetjournals.org/content/17/2/141.abstract
AB Associations of the muscarinic cholinergic antagonist [3H]quinuclidinyl benzilate (3H-QNB) with neural membranes from the frog (Rana pipiens pipiens) are described. This ligand interacts with a single set of identical independent sites on these membranes. The set of sites has characteristics suggesting that it represents a population of muscarinic receptor structures. The first thermodynamic association constant of 3H-QNB with the set of sites is 1.7 ± 0.53 x 109 M-1. The pseudo-first-order rate constant of association is 2.74 ± 0.42 x 106 M-1 sec-1. Temperature studies demonstrate several transitions in both the kinetic and thermodynamic properties of association. Finally, when membrane composition is modified by temperature acclimation of the animals, significant changes are observed in both antagonist and agonist interactions with the receptor structure.