Beta adrenoreceptors in the rabbit bladder detrusor muscle

Journal Article · Wed Feb 01 04:00:00 EST 1984 · J. Pharmacol. Exp. Ther.; (United States)

OSTI ID:6743222

Anderson, G F; Marks, B H

This study examines the beta adrenergic receptors of the rabbit detrusor smooth muscle, employing (/sup 125/I)iodocyanopindolol (ICYP) as a ligand for the binding of beta adrenergic receptors. Saturation binding experiments on the isolated membrane fraction yielded a KD for ICYP of 14.7 pM and a maximum binding of 147.6 fmol/mg of protein. Displacement of labeled ICYP by a series of beta adrenergic agents yielded the following KD values for the combined high and low affinity binding sites: I-propranolol, 0.76 nM; ICI 118,551, 1.7 nM; zinterol, 38.0 nM; metoprolol, 3.5 microM; and practolol, 61.4 microM. When these displacement experimental results were compared to KD values from other reported binding studies with ICYP for beta adrenoreceptors, both the order of potency and the KD values indicated primarily beta-2 adrenergic receptor subtypes. Computer program Scatfit analysis of the displacement curves indicated a single slope and affinity constant for all five beta adrenergic agents. Hofstee plots for zinterol, ICI 118,551 and metoprolol, however, were not linear and indicated that minor populations of beta-1 adrenoreceptors were also present as both high and low affinity binding sites could be defined. It is concluded that the primary receptor population is beta-2 and that this tissue is heterogenous with a small population of beta-1 adrenoreceptors representing approximately 13 to 23% of the total beta adrenoreceptor population.

• Research Organization: Wayne State Univ., Detroit, MI
• OSTI ID: 6743222
• Journal Information: J. Pharmacol. Exp. Ther.; (United States), Journal Name: J. Pharmacol. Exp. Ther.; (United States) Vol. 228:2; ISSN JPETA
• Country of Publication: United States
• Language: English

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551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ADRENALINE
AMINES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
CARDIOTONICS
CARDIOVASCULAR AGENTS
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MUSCLES
NEUROREGULATORS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PHYSIOLOGY
RABBITS
RADIOISOTOPES
RECEPTORS
STEROID HORMONES
SYMPATHOMIMETICS
TRACER TECHNIQUES
VERTEBRATES