Specific binding of [3H]mepyramine to histamine H1-receptors in vascular smooth muscle membranes.
The antagonist-sensitive binding of [3H]mepyramine to beef aortic membranes was as expected for binding to histamine H1-receptors. [3H]mepyramine binds rapidly and in saturable fashion to the specific receptor sites, specific binding reaching equilibrium in 3 min at 37 degrees C. SCATCHARD's analysis of the binding data gave a dissociation constant of 3.0 nM for the radioligand-receptor complex and maximal number of binding sites: 31 fmol/mg protein. In the competition studies histamine H1-antagonists are more potent inhibitors of radioligand binding than H2-antagonist. They inhibit [3H]mepyramine binding in the following order: mepyramine greater than triprolidine greater than promethazine much greater than cimetidine. Binding data are in correlation with the previous pharmacological studies.
D000631:Aminopyridines / Q000378:metabolism*; D000818:Animals; D001011:Aorta / Q000378:metabolism; D002417:Cattle; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D011738:Pyrilamine / Q000378:metabolism*; D011968:Receptors, Histamine / Q000378:metabolism*; D011969:Receptors, Histamine H1 / Q000378:metabolism*; D014316:Tritium
D000631:Aminopyridines; D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D014316:Tritium; D011738:Pyrilamine