Bombesin Stimulates Gastrin Secretion in the Rat without Increasing Serum Calcitonin 1 2

Summary Bombesin was administered to young fasted rats, and blood levels of immunoreactive gastrin and calcitonin (CT) were measured. Doses of bombesin up to 100 μg/rat i.v. did not affect serum calcium or phosphorus. Five minutes after bombesin, 10 or 50 μg/rat, serum gastrin increased 1- to 2-fold and, by 30 min, it was elevated 5- to 10-fold. Time-course and dose-response studies showed that doses of 10–100 μg/rat increased gastrin and that gastrin rose within 5 min after 50 μg/rat and remained elevated for at least 2 hr. Despite bombesin-induced hyper-gastrinemia, CT remained low or undetectable (