In the present study, we investigated the effects of
MCI-727, a new anti-
ulcer agent, on plasma immunoreactive
secretin concentration in rats and dogs using
secretin specific RIA with the
ethanol extraction method. Plasma
secretin levels were increased dose-dependently 10 min after
oral administration of
MCI-727 in rats (control: 5.5 +/- 0.6;
MCI-727, 10 mg/kg: 10.4 +/- 2.6; 30 mg/kg: 15.3 +/- 1.5; 100 mg/kg: 20.7 +/- 2.6 pg/ml, n = 6).
Teprenone also caused a significant increase of plasma
secretin at 10 min after
oral administration at the doses of 30, 100 and 300 mg/kg. Under the same conditions,
MCI-727 and
teprenone did not alter the plasma immunoreactive
gastrin concentration in rats. From the results of the time course study, the increasing effect of
MCI-727 (30 mg/kg, p.o.) on plasma
secretin remained for at least 240 min after administration. On the other hand, the increasing effect of
teprenone (200 mg/kg, p.o.) was only observed at 30 and 60 min after administration. Furthermore,
MCI-727 had increasing effects on plasma
secretin concentration in dogs, but
teprenone had no effects in this species. The volume of pancreatic secretion and the pancreatic
bicarbonate output increased after intra-duodenal administration of
MCI-727 at 30 and 100 mg/kg in rats. Similar effects were also observed with
teprenone (30-300 mg/kg, i.d.) or
secretin (
Secrepan, 0.1-1.0 unit/kg, i.v.).