Intraduodenal Instillation of Acid and Hyperosmolal Solution Suppresses Pentagastrin-Stimulated Acid Secretion But Not Histamine Mobilization in the Rat Stomach

Abstract

In chronic gastric fistula rats provided with a duodenal loop anastomosed to the jejunum (Roux-en-Y). maximal stimulation of acid secretion by continuous intravenous infusion of pentagastrin produced a 15-fold increase of gastric histidine decarboxylase activity. lntraduodenal instillation of 0.20 M HCI or 1200 mOsm × kg⁻¹ solution of polyethylene glycol (PEG) inhibited the maximal acid response to pentagastrin by 61% and hyperosmolal (1200 mOsm × kg⁻¹ of PEG solution) 0.20 M HCI by 79% but did not suppress the pentagastrin-induced increase in enzyme activity. Hence. instillation of HCI and/or hyperosmolal PEG solution in the duodenum depresses the responsiveness of the parietal cells to pentagastrin without interfering with pentagastrin-induced activation of gastric histamine formation.

Key Words:

• Acid inhibition
• acid secretion
• duodenal acidification
• duodenal hypcros-molality
• histidine decarboxylase
• pentagastrin
• rat stomach