Development of a radioiodinated ligand for characterising. cap alpha. /sub 1/-adrenoceptors. [Pentolamine and 2 BETA-(4-hydroxyphenyl)-ethylaminomethyl)-tetralone]
Two ..cap alpha..-adrenoceptor antagonists, phentolamine and 2-(..beta..-(4-hydroxyphenyl)-ethylaminomethyl)-tetralone (BE 2254) which are phenolic derivatives were radioiodinated after chloramine-T oxidation of Na/sup 125/I and the labelled material isolated by chromatography. /sup 125/I-Phentolamine does not bind selectively to ..cap alpha..-adrenoceptors in guinea pig brain whereas the /sup 125/I-BE 2254 derivative binds rapidly, reversibly and with high affinity to these receptors with a K/sub d/ of 230 pM. At low concentrations of /sup 125/I-BE 2254 (< 100 pM) approx. 90% of the bound radioligand is specifically bound and under these conditions drug displacement studies show that the ligand binds predominantly to the ..cap alpha../sub 1/ subclass of adrenoceptors. Binding measurements to kidney and smooth muscle membrane preparations indicate that /sup 125/I-BE 2254 may also be a useful tool in the study of ..cap alpha..-adrenoceptors in peripheral tissues. The high specific activity of /sup 125/I-BE 2254 permits the use of minimal quantities of membrane material for receptor assay and ligand displacement measurements, e.g. 250 ..mu..g per assay tube, and this provides a significant advantage over the use of existing radioligands such as /sup 3/H-prazosin which requires approx. 40 times as much tissue.
- Research Organization:
- Univ. of Melbourne, Australia
- OSTI ID:
- 7093648
- Journal Information:
- Life Sci.; (United States), Vol. 30:11
- Country of Publication:
- United States
- Language:
- English
Similar Records
Photoaffinity cross-linking of a radioiodinated probe, /sup 125/I-A55453, into alpha 1-adrenergic receptors
In vivo binding in rat brain and radiopharmaceutical preparation of radioiodinated HEAT, an alpha-1 adrenoceptor ligand
Related Subjects
IODINE 125
RADIOCHEMISTRY
ORGANIC OXYGEN COMPOUNDS
LABELLING
RADIOPHARMACEUTICALS
CHEMICAL PREPARATION
AMINES
BRAIN
CELL MEMBRANES
GUINEA PIGS
INHIBITION
KIDNEYS
LIGANDS
MUSCLES
PHENOLS
RECEPTORS
SODIUM IODIDES
ALKALI METAL COMPOUNDS
ANIMALS
AROMATICS
BETA DECAY RADIOISOTOPES
BODY
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
HALIDES
HALOGEN COMPOUNDS
HYDROXY COMPOUNDS
INORGANIC PHOSPHORS
INTERMEDIATE MASS NUCLEI
IODIDES
IODINE COMPOUNDS
IODINE ISOTOPES
ISOTOPES
LABELLED COMPOUNDS
MAMMALS
MEMBRANES
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PHOSPHORS
RADIOISOTOPES
RODENTS
SODIUM COMPOUNDS
SYNTHESIS
VERTEBRATES
400702* - Radiochemistry & Nuclear Chemistry- Properties of Radioactive Materials