title: Evidence for alpha 2 adrenergic receptors in bovine cerebral arteries.
abstract: Specific [3H]yohimbine binding to the homogenates of bovine cerebral arteries was saturable and of high affinity (KD = 21 nM) with a Bmax of 720 fmol/mg protein. On the other hand, there was no detectable specific [3H]prazosin binding to these tissues. Scatchard and Hill plot analyses of specific [3H]yohimbine binding indicated one class of binding sites. Specific binding of [3H]yohimbine was displaced effectively by alpha 2 adrenergic agents and less effectively by alpha 1 adrenergic agents. IC50 values for adrenergic drugs of [3H]yohimbine binding were as follows: yohimbine, 55 nM; tramazoline, 270 nM; clonidine, 580 nM; methoxamine, 15 microM; prazosin, 47 microM, phenylephrine, 49 microM; norepinephrine, 60 microM; epinephrine, 150 microM. These results suggest that alpha adrenergic receptors in bovine cerebral artery are mostly of the alpha 2 subtype.
mesh_terms: D000818:Animals; D001099:Arachnoid / Q000098:blood supply; D001665:Binding Sites; D002417:Cattle; D002536:Cerebral Arteries / Q000378:metabolism*; D066298:In Vitro Techniques; D010841:Pia Mater / Q000098:blood supply; D011224:Prazosin / Q000378:metabolism; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D013566:Sympathomimetics / Q000378:metabolism; D015016:Yohimbine / Q000378:metabolism
chemical_list: D011942:Receptors, Adrenergic, alpha; D013566:Sympathomimetics; D015016:Yohimbine; D011224:Prazosin