We examined the pharmacologic effect of beta-methyl-2',6'-dimethyltyrosine-
L-tetrahydroisoquine-3-carboxylic acid ((2 S,3 R)TMT-L-Tic-OH) on G protein
activation in membranes prepared from Chinese Hamster Ovary cells transfec
ted with cDNA of the human delta-opioid receptor. (2S,3R)TMT-L-Tic-OH inhib
ited G protein activation to 58% of basal with an EC50 of 0.72 nM as determ
ined by [S-35]GTP gamma S binding. These findings suggest that (2S,3R)TMT-L
-Tic-OH is a highly potent inverse agonist at the human delta-opioid recept
or. (C) 1999 Elsevier Science B.V. All rights reserved.