Inhibitory and stimulatory effects of secretin on gastric secretion in conscious rats.

1. The effect of pure secretin on gastrin-induced secretion has been studied in conscious rats with Pavlov or Heidenhain pouches.2. Rapid intravenous injection of secretin did not inhibit a plateau secretion of acid in the Heidenhain pouch, but infusion of the same amount of secretin over two hours inhibited secretion in both Heidenhain and Pavlov pouches.3. A rapid intravenous injection of secretin before the onset of gastrin infusion enhanced the acid secretory response to gastrin in both types of pouches.4. Secretin stimulated pepsin secretion.