title: Binding of [3H]-prazosin and [3H]-dihydroergocryptine to rat cardiac alpha-adrenoceptors.
abstract: 1 [3H]-prazosin binds specifically to a single class of alpha-adrenoceptors in rat cardiac membranes (KD25 degrees C = 0.2 nM). 2 That these receptors are of the alpha 1-type was indicated by competition studies, i.e. alpha 1-antagonists such as prazosin and (2-(2,6-dimethoxyphenoxyethyl) aminomethyl-1, 4-benzodioxane (WB 4101) were more potent than the alpha 2-antagonists, yohimbine and piperoxan in inhibiting [3H]-prazosin binding. 3 A comparative study of [3H]-prazosin binding and [3H]-dihydroergocryptine binding to cardiac membranes showed that both [3H]-prazosin and [3H]-dihydroergocryptine (at low concentrations) bind to alpha 2-adrenoceptors, while [3H]-dihydroergocryptine (at higher concentrations) also binds to another class of sites.
mesh_terms: D000818:Animals; D001665:Binding Sites; D004088:Dihydroergotoxine / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D011224:Prazosin / Q000378:metabolism*; D011799:Quinazolines / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000378:metabolism*; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D014316:Tritium
chemical_list: D011799:Quinazolines; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D014316:Tritium; D004088:Dihydroergotoxine; D011224:Prazosin