association ( 1.23 +/- 0.19 x 10 ( 10 ) mol-1 x min-1 and dissociation rate ( 0.19 +/- 0.03 min-1 ) constants were determined in human cortical tissues ; results from studies in rat cortical , and rat diencephalon tissue homogenates produced similar kinetic rate constants . competition studies with a variety of drugs indicated that [ 3h ] carfentanil interacts primarily with mu opioid receptors in the four tissues studied ; the affinities of a series of non-radioactive opioid ligands were essentially identical in the four tissues ( correlation coefficients = 0.88-0.93 ) . naloxone , morphine , dago [ ( d-ala2-mephe4-gly-ol5 ] enkephalin ) , dadl [ ( d-ala2-d-leu5 ] enkephalin ) and ekc ( ehtylketazocine ) potently displaced specific [ 3h ] carfentanil binding with nm potency while the kappa agonist u-69593 , the sigma agonists ( + ) -skf 10047 , ( + ) -3-ppp [ 3-hydroxyphenyl ) -n-propylpiperidine ) and haloperidol and pcp ( phencyclidine ) were less potent displacing agents .
C0525773
dago
C0014298
enkephalin