Identification and characterization of (/sup 3/H)-rauwolscine binding to alpha2-adrenoceptors in the canine saphenous vein
The biochemical exploration of the alpha2-adrenergic receptors was investigated in the canine saphenous vein using the highly selective alpha2-adrenergic antagonist rauwolscine as a tritiated ligand. Following an enzymatic digestive pretreatment, the authors isolated a purified smooth muscle cell membranes fraction from saphenous veins in quantity sufficient to permit them to study the venous alpha2-adrenoreceptor content. The binding of tritiated rauwolscine was rapid, specific, saturable and reversible. The presence of high affinity sites with a density of binding Bmax of 125.2 /+ -/ 43.1 fmol/mg protein was demonstrated on a unique class of non interacting sites. The kinetically derived Kd was 1.28 nM, in good agreement with the value obtained from saturation isotherms. The pharmacological profile of these sites was assessed by the comparison of the potency of alpha-adrenergic agonists and antagonists to inhibit 1 nM (/sup 3/H)-rauwolscine. Their efficacy was respectively: rauwolscine > phentolamine > RX 781094 > clonidine >> prazosin > (-)-phenylephrine > (-)-noradrenaline. The results showed that (/sup 3/H)-rauwolscine bound specifically to sites in their membranal preparation, which had the pharmacological characteristics of the alpha2-adrenoceptors. The correlation between biochemical and pharmacological data revealed the usefulness of binding methods in the further study of adrenergic mechanisms in the canine saphenous vein.
- Research Organization:
- Centre de Recherche Pierre Fabre, Castres (France)
- OSTI ID:
- 6143117
- Journal Information:
- Life Sci.; (United States), Vol. 43:24
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SYMPATHOLYTICS
BIOCHEMICAL REACTION KINETICS
SYMPATHOMIMETICS
RECEPTORS
CELL MEMBRANES
CHEMICAL COMPOSITION
DOGS
LIGANDS
MUSCLES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VEINS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BLOOD VESSELS
BODY
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
DRUGS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
ORGANIC COMPOUNDS
ORGANS
PROTEINS
REACTION KINETICS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques