Synthesis and characterization of arylamine derivatives of rauwolscine as molecular probes for alpha 2-adrenergic receptors

Journal Article · Mon Jun 01 04:00:00 EDT 1987 · Hypertension (Dallas); (United States)

DOI:https://doi.org/10.1161/01.HYP.9.6_Pt_2.III120· OSTI ID:6326647

Lanier, S M; Graham, R M; Hess, H J; Grodski, A; Repaske, M G; Nunnari, J M; Limbird, L E; Homcy, C J

The selective alpha 2-adrenergic receptor antagonist rauwolscine was structurally modified to yield a series of arylamine carboxamide derivatives, which were investigated as potential molecular probes for the localization and structural characterization of alpha 2-adrenergic receptors. The arylamine carboxamides differ in the number of carbon atoms separating the reactive phenyl moiety from the fused ring structure of the parent compound, rauwolscine carboxylate. Competitive inhibition studies with (/sup 3/H)rauwolscine in rat kidney membranes indicate that the affinity for the carboxamide derivatives is inversely related to the length of the carbon spacer arm with rauwolscine 4-aminophenyl carboxamide exhibiting the highest affinity (Kd = 2.3 +/- 0.2 nM). Radioiodination of rau-AMPC yields a ligand, /sup 125/I-rau-AMPC, which binds to rat kidney alpha 2-adrenergic receptors with high affinity, as determined by both kinetic analysis (Kd = k2/k1 = 0.016 min-1/2.1 X 10(7) M-1 min-1 = 0.76 nM) and equilibrium binding studies (Kd = 0.78 +/- 0.16 nM). /sup 125/I-rau-AMPC was quantitatively converted to the photolabile arylazide derivative 17 alpha-hydroxy-20 alpha-yohimban-16 beta-(N-4-azido-3-(/sup 125/I)iodophenyl) carboxamide (/sup 125/I-rau-AZPC). In a partially purified receptor preparation from porcine brain, this compound photolabels a major (Mr = 62,000) peptide. The labeling of this peptide is inhibited by adrenergic agonists and antagonists with a rank order of potency consistent with an alpha 2-adrenergic receptor binding site. Both /sup 125/I-rau-AMPC and the photolabile arylazide derivative, /sup 125/I-rau-AZPC, should prove useful as molecular probes for the structural and biochemical characterization of alpha 2-adrenergic receptors.

• Research Organization: Massachusetts General Hospital, Harvard Medical School, Boston
• OSTI ID: 6326647
• Journal Information: Hypertension (Dallas); (United States), Journal Name: Hypertension (Dallas); (United States) Vol. 9; ISSN HPRTD
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AFFINITY
AMINES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZIDES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BIOSYNTHESIS
BLOOD
BLOOD CELLS
BLOOD PLATELETS
BODY
BODY FLUIDS
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL COMPOSITION
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
KINETICS
LABELLED COMPOUNDS
LIGANDS
MAMMALS
MATERIALS
MEMBRANE PROTEINS
MEMBRANES
NITROGEN COMPOUNDS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SYMPATHOMIMETICS
SYNTHESIS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES