Interaction of a vasopressin antagonist with vasopressin receptors in the septum of the rat brain
The ability of d(CH2)5-Tyr(Me)-arginine-8-vasopressin, an antagonist of peripheral pressoric (V1-type) vasopressin receptors, to label vasopressin binding sites in the septum of the rat brain was evaluated. Using crude membrane preparations from the septum, /sup 3/H-arginine-8-vasopressin (AVP) specifically labels a single class of binding sites with a Kd of 2.9 nM and maximum binding site concentration of 19.8 fmole/mg protein. /sup 3/H-Antag also labels a single class of membrane sites but with higher affinity (Kd = 0.47 nM) and lower capacity (10.1 fmole/mg protein) than /sup 3/H-AVP. The rank order of potency of various competitor peptides for /sup 3/H-AVP and /sup 3/H-Antag binding was similar. Oxytocin was 100-1,000 fold less potent than AVP in competing for binding with both ligands. /sup 3/H-AVP and /sup 3/H-Antag showed similar labeling patterns when incubated with septal tissue slices. Unlabeled Antag also effectively antagonized vasopressin-stimulated phosphatidylinositol hydrolysis in septal tissue slices.
- Research Organization:
- Veterans Administration Medical Center, Seattle, WA (USA)
- OSTI ID:
- 6354119
- Journal Information:
- Synapse; (United States), Journal Name: Synapse; (United States) Vol. 2:3; ISSN SYNAE
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTORADIOGRAPHY
BIOCHEMICAL REACTION KINETICS
BODY
BRAIN
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
HORMONES
IN VITRO
KINETICS
LABELLED COMPOUNDS
LABELLING
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY HORMONES
PROTEINS
RATS
REACTION KINETICS
RECEPTORS
RODENTS
TRITIUM COMPOUNDS
VASOPRESSIN
VERTEBRATES