Characterization of the hepatic alpha 1B-adrenoceptors of rats, mice and hamsters.
The alpha 1-adrenoceptors present in liver membranes from rats, hamsters and mice were characterized using [3H]prazosin. In the liver membranes from the three species a relatively large number of receptors was observed (500-900 fmol/mg of protein) and the affinities for [3H]prazosin were very similar (0.2-0.3 nM). Membrane preincubation with 10 microM chloroethylclonidine markedly decreased [3H]prazosin binding and higher concentrations essentially abolished specific binding of this radioligand. Binding competition experiments indicated the following orders of potency: a) for agonists: oxymetazoline > epinephrine > or = norepinephrine >> methoxamine and b) for antagonists: prazosin > WB 4101 > or = phentolamine = benoxathian > 5-methyl urapidil. The affinity for (+)niguldipine was also low but there was variation between the three species. Total RNA obtained from the liver of these species hybridized with the alpha 1B-adrenergic cDNA probe. The data suggest that these receptors correspond to the alpha 1B subtype.
García-Sáinz
J A
JA
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D. F.
Casas-González
P
P
Romero-Avila
M T
MT
González-Espinosa
C
C
D000316:Adrenergic alpha-Agonists / Q000378:metabolism; D000317:Adrenergic alpha-Antagonists / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D006224:Cricetinae; D004095:Dihydropyridines / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D008647:Mesocricetus; D051379:Mice; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects / Q000378:metabolism*; D013045:Species Specificity
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D004095:Dihydropyridines; D011942:Receptors, Adrenergic, alpha; C051731:chlorethylclonidine; D003000:Clonidine; D011224:Prazosin; C054074:niguldipine