title: [Binding of [3H] dihydroetorphine to opioid receptors in rat brain membrane].
abstract: OBJECTIVE
  To study the binding characteristics of dihydroetorphine (DHE) to opioid receptors.
  
  
  METHODS
  The binding of [3H] DHE to rat brain membrane opioid receptors was observed by radioligand binding study.
  
  
  RESULTS
  Saturation study showed the binding of [3H] DHE to rat brain membrane presented a single high-affinity class of binding sites with Kd = 0.19 nmol.L-1 and Bmax = 115 pmol/g protein. Kinetics study showed the association rate of [3H] DHE to opioid receptor was very rapid and dissociation very slow. NaCl 100 mmol.L-1 + guanosine triphosphate (GTP) 50 mumol.L-1 inhibited the binding of [3H] DHE and made Kd increase to 7.87 nmol.L-1, without effect on Bmax. Competitive inhibition of agonists and antagonists indicated that the affinity of [3H]DHE to mu opioid receptor was higher than to delta and kappa opioid receptors.
  
  
  CONCLUSIONS
  DHE is a selective agonist of mu opioid receptors.
authors.affiliation: Institute of Pharmacology & Toxicology, Academy of Military Medical Sciences, Beijing, China.
authors.forename: D X
authors.initials: DX
authors.lastname: Wang
authors.forename: B Y
authors.initials: BY
authors.lastname: Qin
mesh_terms: D000701:Analgesics, Opioid / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D005048:Etorphine / Q000031:analogs & derivatives* / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000378:metabolism*
chemical_list: D000701:Analgesics, Opioid; D011957:Receptors, Opioid; D005048:Etorphine; C034765:18,19-dihydroetorphine