Alpha-adrenoceptors in dog mesenteric vessels--subcellular distribution and number of ( sup 3 H)prazosin and ( sup 3 H)rauwolscine binding sites

Journal Article · Sat Mar 31 23:00:00 EST 1990 · Journal of Cardiovascular Pharmacology; (USA)

DOI:https://doi.org/10.1097/00005344-199004000-00001· OSTI ID:6940474

Shi, A G; Ahmad, S; Kwan, C Y; Daniel, E E ^[1]

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1. McMaster Univ., Hamilton, Ontario (Canada)

Binding of the alpha-adrenergic antagonists ({sup 3}H)prazosin and ({sup 3}H)rauwolscine to well-characterized subcellular membrane fractions isolated from dog mesenteric arteries and veins was studied. Binding of both ligands was saturable with Kd values of 0.5 +/- 0.1 nM for ({sup 3}H)prazosin and 5.85 +/- 0.85 nM for ({sup 3}H)rauwolscine in arteries, and 0.87 +/- 0.4 nM for ({sup 3}H)prazosin and 6.6 +/- 1.5 nM for ({sup 3}H)rauwolscine in veins. In veins, the maximum number of binding sites for ({sup 3}H)rauwolscine was higher than that for ({sup 3}H)prazosin, whereas in arteries the maximum number of binding sites for each ligand was similar. In microsomes from dog aorta, the maximum number of bindings sites for ({sup 3}H)prazosin was higher than that for ({sup 3}H)rauwolscine. Neuronal membrane contamination in these studies was minimized by dissection procedures and evaluated by the comparison of ({sup 3}H)saxitoxin binding in various preparations. Only mesenteric veins responded functionally to agonists acting on alpha 2 adrenoceptors. This study thus identified two distinct populations of ({sup 3}H)prazosin and ({sup 3}H)rauwolscine binding sites in the plasma membranes of dog mesenteric vessels and suggests that a much higher density of alpha 2-compared to alpha 1-adrenoceptor binding sites is required for a contractile response.

• OSTI ID: 6940474
• Journal Information: Journal of Cardiovascular Pharmacology; (USA), Journal Name: Journal of Cardiovascular Pharmacology; (USA) Vol. 15:4; ISSN 0160-2446; ISSN JCPCD
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
ARTERIES
AUTONOMIC NERVOUS SYSTEM AGENTS
BIOCHEMICAL REACTION KINETICS
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CELL MEMBRANES
CYTOCHROME OXIDASE
DISTRIBUTION
DOGS
DRUGS
ENZYMES
HAEM DEHYDROGENASES
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
MUSCLES
ORGANIC COMPOUNDS
ORGANS
OXIDOREDUCTASES
PROTEINS
RADIOASSAY
REACTION KINETICS
RECEPTORS
SUBCELLULAR DISTRIBUTION
SYMPATHOMIMETICS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VEINS
VERTEBRATES