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Inhibition by cations of antagonist binding to histamine H1-receptors
J M Treherne1, J S Stern, W J Flack
1Department of Pharmacology, University of Cambridge, U.K.
Agents and Actions. Supplements
|January 1, 1991
Abstract:
The binding of the quaternary radioligand [3H] QMDP to the histamine H1-receptor was inhibited by a series of mono- and di-valent cations. The order of potency was Hg2+ greater than Cd2+ greater than Zn2+ greater than Ni2+ greater than Co2+ greater than Mn2+ greater than Ca2+ greater than Mg2+ greater than Li+ = Na+ greater than K+ greater than Cs+. The binding of [3H] mepyramine, a tertiary amine, was inhibited by the divalent cations to a similar extent as the binding of [3H] QMDP. Li+ also had a similar potency against the two ligands, but Na+ was a much more potent inhibitor of the binding of [3H] QMDP than that of [3H] mepyramine.