title: 3H-mepyramine binding and histamine-stimulated cAMP accumulation in mammalian retina.
abstract: The specific binding of different amounts of 3H-mepyramine to the bovine retina revealed a quasi-hyperbolic curve which approached saturation at 3H-ligand concentration over 9-12 nM. Scatchard analysis of the binding data showed two binding sites with KD values of 0.76 nM and 7.3 nM and Bmax of 49.3 and 194.6 fmole/mg protein, respectively. In the guinea-pig brain 3H-mepyramine bound to a single population of binding sites with KD value of 1.6 nM and Bmax of 291 fmole/mg protein. Various H1-antihistamines were potent competitors of the 3H-mepyramine binding: there was a big difference in potency of d- and 1-chlorpheniramine in both membrane preparations. In the rabbit retina slices histamine, in contrast to dopamine, weakly stimulated cAMP accumulation. The data suggest that the mammalian retina may possess histamine receptors.
mesh_terms: D000631:Aminopyridines / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism; D002417:Cattle; D000242:Cyclic AMP / Q000378:metabolism*; D004298:Dopamine / Q000494:pharmacology; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D011738:Pyrilamine / Q000378:metabolism*; D011817:Rabbits; D011968:Receptors, Histamine / Q000032:analysis; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D014316:Tritium
chemical_list: D000631:Aminopyridines; D011968:Receptors, Histamine; D014316:Tritium; D006632:Histamine; D000242:Cyclic AMP; D011738:Pyrilamine; D004298:Dopamine