Opioid binding sites in the guinea pig and rat kidney: Radioligand homogenate binding and autoradiography

Journal Article · Mon Jul 01 00:00:00 EDT 1991 · Molecular Pharmacology; (United States)

OSTI ID:5463829

Dissanayake, V U; Hughes, J; Hunter, J C ^[1]

---

1. Parke-Davis Research Unit, Addenbrookes Hospital Site, Cambridge (England)

The specific binding of the selective {mu}-, {delta}-, and {kappa}-opioid ligands (3H)(D-Ala2,MePhe4,Gly-ol5)enkephalin ((3H) DAGOL), (3H)(D-Pen2,D-Pen5)enkephalin ((3H)DPDPE), and (3H)U69593, respectively, to crude membranes of the guinea pig and rat whole kidney, kidney cortex, and kidney medulla was investigated. In addition, the distribution of specific 3H-opioid binding sites in the guinea pig and rat kidney was visualized by autoradiography. Homogenate binding and autoradiography demonstrated the absence of {mu}- and {kappa}-opioid binding sites in the guinea pig kidney. No opioid binding sites were demonstrable in the rat kidney. In the guinea pig whole kidney, cortex, and medulla, saturation studies demonstrated that (3H)DPDPE bound with high affinity (KD = 2.6-3.5 nM) to an apparently homogeneous population of binding sites (Bmax = 8.4-30 fmol/mg of protein). Competition studies using several opioid compounds confirmed the nature of the {delta}-opioid binding site. Autoradiography experiments demonstrated that specific (3H)DPDPE binding sites were distributed radially in regions of the inner and outer medulla and at the corticomedullary junction of the guinea pig kidney. Computer-assisted image analysis of saturation data yielded KD values (4.5-5.0 nM) that were in good agreement with those obtained from the homogenate binding studies. Further investigation of the {delta}-opioid binding site in medulla homogenates, using agonist ((3H)DPDPE) and antagonist ((3H)diprenorphine) binding in the presence of Na+, Mg2+, and nucleotides, suggested that the {delta}-opioid site is linked to a second messenger system via a GTP-binding protein. Further studies are required to establish the precise localization of the {delta} binding site in the guinea pig kidney and to determine the nature of the second messenger linked to the GTP-binding protein in the medulla.

• OSTI ID: 5463829
• Journal Information: Molecular Pharmacology; (United States), Vol. 40:1; ISSN 0026-895X
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ENKEPHALINS
RECEPTORS
TISSUE DISTRIBUTION
ANALGESICS
AUTORADIOGRAPHY
BIOCHEMICAL REACTION KINETICS
CATIONS
CELL MEMBRANES
CPB
GUINEA PIGS
KIDNEYS
NUCLEOTIDES
PHARMACOLOGY
PYRROLIDINES
RATS
TRITIUM COMPOUNDS
AMINES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
AZOLES
BODY
CELL CONSTITUENTS
CENTRAL NERVOUS SYSTEM DEPRESSANTS
CHARGED PARTICLES
DISTRIBUTION
DRUGS
ENDORPHINS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
IONS
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NEUROREGULATORS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PEPTIDES
POLYPEPTIDES
PROTEINS
PYRROLES
REACTION KINETICS
RODENTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques