Inhibition by cations of antagonist binding to histamine H1-receptors.
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.
Department of Pharmacology, University of Cambridge, U.K.
J M
JM
Treherne
J S
JS
Stern
W J
WJ
Flack
J M
JM
Young
D000818:Animals; D002412:Cations / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism; D006168:Guinea Pigs; D006634:Histamine H1 Antagonists / Q000378:metabolism*; D008094:Lithium / Q000494:pharmacology; D008297:Male; D008628:Mercury / Q000494:pharmacology; D009966:Orphenadrine / Q000031:analogs & derivatives / Q000378:metabolism; D011738:Pyrilamine / Q000378:metabolism; D011969:Receptors, Histamine H1 / Q000187:drug effects / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology; D014316:Tritium
D002412:Cations; D006634:Histamine H1 Antagonists; D011969:Receptors, Histamine H1; D014316:Tritium; C057530:N-methyl-4-methyldiphenhydramine; D008094:Lithium; D012964:Sodium; D009966:Orphenadrine; D008628:Mercury; D011738:Pyrilamine