Re-examination of [3H]mepyramine binding assay for histamine H1 receptor using quinine.
[3H]Mepyramine, a potent antagonist of the histamine H1 receptor, has been widely used as a radioligand binding assay for the H1 receptor. Previously, we purified a mepyramine binding protein (MBP) from rat liver, but found that its partial amino acid sequences were very similar to those of debrisoquine 4-hydroxylase isozymes (P450 db1 and db2), which are members of the superfamily of cytochrome P450. Using cloned histamine H1 receptor cDNA, we found that [3H]mepyramine could bind only the H1 receptor and did not bind MBP in the presence of 10(-5) M quinine, an inhibitor of debrisoquine 4-hydroxylase isozymes. We developed a method to determine the contents of the H1 receptor and MBP separately using [3H]mepyramine and quinine and found that MBP is abundant in certain areas of bovine brain.
Liu
Y Q
YQ
Department of Pharmacology II, Faculty of Medicine, Osaka University, Suita, Japan.
Horio
Y
Y
Mizuguchi
H
H
Fujimoto
K
K
Imamura
I
I
Abe
Y
Y
Fukui
H
H
D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D005910:Glioma; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D009928:Organ Specificity; D011738:Pyrilamine / Q000378:metabolism*; D011803:Quinine / Q000494:pharmacology*; D011869:Radioligand Assay / Q000379:methods; D051381:Rats; D011969:Receptors, Histamine H1 / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014316:Tritium; D014407:Tumor Cells, Cultured
D011969:Receptors, Histamine H1; D014316:Tritium; D011803:Quinine; D011738:Pyrilamine