Demonstration of. cap alpha. /sub 2/-adrenergic receptors in rat pancreatic islets using radioligand binding
The type of the ..cap alpha..-adrenergic receptors on rat pancreatic islet cells was characterized directly using specific radioligands and displacement agonists and antagonists. Scatchard plots for binding of (/sup 3/H)clonidine (..cap alpha../sub 2/-agonist) revealed a dissociation constant, K/sub d/ of 0.542 +/- 0.1 nM and density of binding sites (B/sub max/) of 50.4 +/- 3.6 fmole/mg protein. Similar values were obtained with (/sup 3/H)dihydroergocryptine (antagonist). The various agonists displaced (/sup 3/H)clonidine with the following order of potency: clonidine > epinephrine approx. = norepinephrine > isoproterenol. Yohimbine, the ..cap alpha../sub 2/-antagonist, was very effective in displacing (/sup 3/H)clonidine, whereas the ..cap alpha../sub 1/-antagonist, prazosin, was much less effective. The data indicate that the ..cap alpha..-adrenergic receptors on rat pancreatic islets are of the ..cap alpha../sub 2/ subtype.
- Research Organization:
- New York Univ. School of Medicine, NY
- OSTI ID:
- 6438020
- Journal Information:
- Proc. Soc. Exp. Biol. Med.; (United States), Journal Name: Proc. Soc. Exp. Biol. Med.; (United States) Vol. 171:2; ISSN PSEBA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ADRENALINE
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BINDING ENERGY
BIOCHEMICAL REACTION KINETICS
BODY
CARDIOTONICS
CARDIOVASCULAR AGENTS
DIGESTIVE SYSTEM
DRUGS
ENDOCRINE GLANDS
ENERGY
GLANDS
HORMONES
KINETICS
LABELLED COMPOUNDS
MAMMALS
NEUROREGULATORS
ORGANS
PANCREAS
RADIOASSAY
RATS
REACTION KINETICS
RECEPTORS
RODENTS
STEROID HORMONES
SYMPATHOMIMETICS
TRITIUM COMPOUNDS
VERTEBRATES