Characterization of beta-adrenergic receptors in duck cerebral cortex.
beta-adrenoceptor binding sites were characterized in duck cerebral cortex by an in vitro binding technique, using [3H]dihydroalprenolol ([3H]DHA) as a receptor-specific radioligand. The specific binding of [3H]DHA to duck cerebral cortical membranes was found to be rapid, stable, saturable, reversible, and of high affinity. Saturation analysis resulted in a linear Scatchard plot suggesting binding to a single class of receptor binding sites with high affinity (Kd = 1.18 nM) and high capacity (Bmax = 162 fmol/mg protein). Competition studies showed the following relative rank order of potency of various compounds to inhibit the [3H]DHA binding: antagonists--ICI 118,551 > S(-)-propranolol >> betaxolol, yohimbine, WB-4101, prazosin, mianserine; agonists--isoprenaline approximately equal to fenoterol > salbutamol >> clonidine, phenylephrine. The obtained data suggest that in duck cerebral cortex beta-adrenergic receptors (like those described in brains of chick and pigeon) are of the beta 2 subtype. This is in contrast to what has been reported for the mammalian brain, where--among beta-adrenoceptors--the beta 1 subtype is predominant.
Zawilska
J B
JB
Department of Pharmacodynamics, Medical University of Lódź, Poland.
Zalewska-Kaszubska
J
J
Marczak
G
G
Górska
D
D
Woldan-Tambor
A
A
D000319:Adrenergic beta-Antagonists / Q000378:metabolism; D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D004372:Ducks / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D011433:Propranolol / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism
D000319:Adrenergic beta-Antagonists; D011943:Receptors, Adrenergic, beta; D018343:Receptors, Adrenergic, beta-2; D011433:Propranolol