Characterization of the alpha 1-adrenoceptors of cat liver. Predominance of the alpha 1A-adrenergic subtype.
The alpha 1-adrenoceptors present in the liver of cats were characterized using [3H]prazosin. This radioligand binds to cat liver membranes with high affinity ((KD 0.79 nM) to a moderately abundant number of sites (160 fmol/mg of protein). This sites were characterized pharmacologically, by binding competition, observing the following orders of potency: a) for agonists: oxymetazoline > epinephrine = norepinephrine >> methoxamine, and b) for antagonists: WB4101 > or = prazosin > or = (+) niguldipine > or = benoxathian > or = spiperone = 5-methyl-urapidil > phentolamine > BMY 7378. These data suggested that cat liver expresses alpha 1A-adrenoceptors. Expression of the mRNA for this receptor was confirmed by RT-PCR.
García-Sáinz
J A
JA
Departamento de Bioenergética y Biomembranas, Universidad Nacional Autónoma de México, México.
García-Caballero
A
A
González-Espinosa
C
C
D000818:Animals; D001667:Binding, Competitive; D002415:Cats; D004305:Dose-Response Relationship, Drug; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011224:Prazosin / Q000494:pharmacology; D011869:Radioligand Assay; D018340:Receptors, Adrenergic, alpha-1 / Q000145:classification / Q000378:metabolism*
D018340:Receptors, Adrenergic, alpha-1; D011224:Prazosin