Conjugation of 1-naphthol in the gastric mucosa of guinea pigs.

1-Naphthol was conjugated in tissue pieces of the gastric wall to naphthol glucuronide (85%) and naphthol sulfate (15%). There was no regioselectivity in different parts of the stomach. In separated gastric mucosal cell populations, the activities of both transferases were highest in the mucous cell fraction (apparent Vmax of glucuronidation: 0.83 nmol/mg protein/min; apparent Vmax of sulfation: 0.11) with only little, or no activity in chief cells and parietal cells. Immunohistochemically glucuronosyltransferase 1 was predominantly localized in surface mucous cells. In conclusion, the gastric mucosa is an important organ for phase II biotransformation.