Heterogeneity of alpha1 receptors associated with vascular smooth muscle: evidence from functional and ligand binding studies

Journal Article · Mon Aug 10 00:00:00 EDT 1987 · Life Sci.; (United States)

DOI:https://doi.org/10.1016/0024-3205(87)90445-0· OSTI ID:6157430

Babich, M; Pedigo, N W; Butler, B T; Piascik, M T

The nature of the alpha1 receptor associated with rabbit aorta has been examined in functional and receptor binding studies. In isolated aortic rings the dose-response curve for (-)metaraminol was not parallel to that of (-)epinephrine, (-)norepinephrine or (-)phenylephrine. Following inactivation of a portion of the alpha receptors with phenoxybenzamine, the occupancy versus response relationship for metaraminol, in contrast to the other test agonists, was biphasic. In microsomes prepared from aorta, metaraminol bound to two classes of sites labelled by the selective alpha1 antagonist (TH) prazosin. Norepinephrine also bound to two sites on the alpha receptor in all three preparations tested. The Scatchard plot of (TH)prazosin binding to microsomes prepared from frozen aorta was curvilinear. Estimates of the affinities and site densities were 49.6 +/- 15.3 pM and 44.8 +/- 11.8 pmol/gm protein and 1.0 +/- 0.2 nM and 43.8 +/- 17.4 pmol/gm for the high and low affinity sites, respectively. These data are consistent with the idea that there are subtypes of the alpha1 receptor. 33 references, 5 figures.

• Research Organization: Univ. of Kentucky Medical Center, Lexington
• OSTI ID: 6157430
• Journal Information: Life Sci.; (United States), Vol. 41:6
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
MUSCLES
RECEPTORS
BIOCHEMICAL REACTION KINETICS
AFFINITY
AORTA
DOSE-RESPONSE RELATIONSHIPS
EXPERIMENTAL DATA
LIGANDS
MICROSOMES
RABBITS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
ARTERIES
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
DATA
INFORMATION
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
NUMERICAL DATA
ORGANOIDS
ORGANS
REACTION KINETICS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques