Pharmacologic profile of TS-941, a new benzodiazepine derivative cholecystokinin-receptor antagonist, in in vitro isolated rat pancreatic acini.
We investigated the pharmacologic characteristics of a newly developed benzodiazepine derivative (S)-(-)-N-[2,3-dihydro-2-oxo-5-phenyl-1-[(1H-tetrazol-5-yl)methyl] -1H-1,4-benzodiazepine-3-yl]-2-indolecarboxamide (TS-941), a cholecystokinin type A (CCK-A)-receptor antagonist, in the isolated rat pancreatic acini and compared with those of well-known CCK-A-receptor antagonists, devazepide and loxiglumide. TS-941 inhibited CCK-8-stimulated amylase release concentration dependently, as did devazepide and loxiglumide, with a half-maximal inhibition (IC50) at 78.6 +/- 10.3 nM. TS-941 was approximately 23 times less potent than devazepide (IC50, 3.4 +/- 0.3 nM), but was 50 times more potent than loxiglumide (IC50, 3,966 +/- 544 nM) in inhibiting 100 pM CCK-8-stimulated amylase release from rat pancreatic acini. TS-941 had a fivefold lower selectivity than devazepide for pancreatic CCK (CCK-A) over brain CCK (CCK-B) receptors but fourfold greater than loxiglumide when IC50 values for inhibition of [125I]CCK-8 binding in isolated acini and cerebral cortex were compared. The antagonism produced by TS-941 was specific for CCK in that the effects of other receptor secretagogues or agents bypassing receptors were not altered. TS-941 caused a parallel rightward shift of the entire dose-response curve for CCK-8-stimulated amylase release without altering the maximal increase, as did devazepide and loxiglumide. TS-941, whether added at the beginning or 20 min after the CCK-8 stimulation, inhibited amylase release. TS-941 caused a concentration-dependent residual inhibition of the action of CCK-8. The acini, once incubated with a high concentration of TS-941 (10 microM; 127 times IC50) for 30 min, was 10-fold less sensitive to CCK-8 than the acini preincubated without TS-941, whereas the sensitivity and the responsiveness to CCK-8 stimulation of those incubated with a low concentration of TS-941 (1.0 microM) were similar to the control acini. These results indicate that TS-941 is a potent, competitive, and selective CCK-A receptor antagonist for the pancreas.
Tashiro
M
M
Third Department of Internal Medicine, University of Occupational and Environmental Health, Japan, School of Medicine, Kitakyushu.
Hirohata
Y
Y
Kihara
Y
Y
Akiyama
T
T
Otsuki
M
M
D000681:Amylases / Q000378:metabolism; D000818:Animals; D001569:Benzodiazepines / Q000494:pharmacology*; D001667:Binding, Competitive; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D020109:Devazepide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006727:Hormone Antagonists / Q000494:pharmacology*; D008297:Male; D010179:Pancreas / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011377:Proglumide / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors*; D012844:Sincalide / Q000378:metabolism
D006727:Hormone Antagonists; D011949:Receptors, Cholecystokinin; C115763:TS 941; D001569:Benzodiazepines; C053737:loxiglumide; D000681:Amylases; D011377:Proglumide; D020109:Devazepide; D012844:Sincalide