Inhibitory effect of L-glutamine on gastric irritation and back diffusion of gastric acid in response to aspirin in the rat.

L-Glutamine given orally at 750 mg/kg significantly reduced the formation of gastric mucosal lesions induced by aspirin at 100 mg/kg at 1, 3, and 7 hours in pylorus-ligated rats. L-Glutamine markedly inhibited the loss of H+ and a corresponding increment of Na+ through the aspirin-damaged mucosal barrier, which suggests inhibition of acid back diffusion as the mechanism of action. In vagotomized rats, the diffusion of H+ from the instilled acid solution into the gastric mucosa and outflux of Na+ from the mucosa into the lumen was so strong that aspirin could not show any acceleration of a back diffusion of H+ in contrast to the aspirin-free group. However, L-Glutamine given with or without aspirin inhibited the group. However, L-Glutamine given with or without aspirin inhibited the back diffusion of H+ instilled into the vagotomized rat stomach.