Localization of opiate binding sites in kidney and adrenal gland of the rat.
[3H]ethylketocyclazocine (EKC) and [3H]etorphine bind to an apparent single class of sites in the rat kidney (kd = 7.3 and 5.2 nM; Bmax = 33.2 and 59.6 fmol/mg protein, respectively). No detectable binding was observed for [3H]dihydromorphine and [3H]D-Ala2,D-Leu5 enkephalin. Ligand selectivity pattern strongly suggests that both [3H]EKC and [3H]etorphine label a kappa opiate binding site since (-)bremazocine greater than EKC greater than etorphine greater than naloxone greater than dynorphin A much greater than beta-endorphin. In the adrenal gland, [3H]EKC also labels a single class of sites (Kd = 20.1 nM; Bmax = 74.7 fmol/mg protein) while no specific binding was seen with mu and delta ligands. Autoradiographically, [3H]EKC and [3H]etorphine binding sites are highly localized in kidney cortex compared to outer and inner medulla. Rather surprisingly, [3H]EKC binding sites in the adrenal are highly localized in the cortex with only low densities in the medulla. We are currently investigating the possible physiological roles of kappa agonists in kidney and adrenal gland functions.
D000311:Adrenal Glands / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography; D007668:Kidney / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D014316:Tritium
D011957:Receptors, Opioid; D014316:Tritium