[Effects of single and combined administration FM-100 and cimetidine on serum gastrin levels in rats].

Antral pH was varied by an intragastric administration of a buffer solution with weak or strong acidity. There is a highly significant correlation between the intragastric pH and serum gastrin level (SG). FM-100 (800 mg/kg, i.d.) decreased SG independently of the intragastric pH, but cimetidine (400 mg/kg, i.d.) did not affect SG beyond the control range. The combination of FM-100 and cimetidine decreased SG significantly as compared with that after cimetidine alone; however, the SG was significantly higher than that after FM-100 alone. These results suggest that FM-100 inhibited gastrin release from the antrum independently of a feedback mechanism due to the intragastric pH, cimetidine increased SG dependently on the feedback mechanism, and FM-100 inhibited the increase in SG after cimetidine in pylorus-ligated rats.