Rat gastric secretion studies with synthetic gastrin-like tetrapeptide.

Gastric acid and pepsin secretions were measured in the perfusing rat stomach preparation with sodium-citrate-phosphate buffer, pH 6.6. In anesthetized rat stomach preparation, acid output in both basal and stimulated conditions seemed to be small, but pepsin output was observed even in a short period. In the rats which were fed freely just before use, basal pepsin output was significantly lower than that of fasted rats, although in the basal acid output and in the acid and pepsin output during stimulation in both groups, there was no difference statistically. Intravenous infusion of tetragastrin (1, 2, 4, 8, 16 and 32 microgram/kg/hr) produced a dose dependent acid and pepsin secretions. Tetragastrin, at the dose of 8 microgram/kg/hr, stimulated acid and pepsin output. Acid output was kept constant for three hours, but pepsin output was made to peak within an hour and formed a plateau after 1.5 hours at a level of 30% of peak pepsin output.