Effects of fluoride on structure and function of canine gastric mucosa.

These studies were done to determine the effects of fluoride (F) on the structure and function of the canine gastric mucosa and the possible protective effects of 16,16-dimethyl-prostaglandin E2 (dmPGE2). A portion of the stomach with its vascular supply intact was mounted in a two-compartment chamber, one side of which contained a control solution. Minor effects were caused by exposure to 1 mmol/liter F. Both 5 and 10 mmol/liter F caused marked increases in the fluxes of water and Na, K, and H ions; mucus secretion; and tissue swelling and redness. The extent of these changes did not increase appreciably upon exposure to 50 or 100 mmol/liter F. Histological findings included marked thinning of the surface cell layer, reduced uptake of PAS stain, localized exfoliation and necrosis of surface cells, acute gastritis, and edema. It was concluded that: (1) the threshold F concentration for effects on the structure and function of the gastric mucosa was approximately 1 mmol/liter; (2) the maximum or near-maximum effects were caused by 10 mmol/liter F; (3) the effects persisted for at least 6 hr after the exposure; and (4) dmPGE2 (0.5 microg/ml) did not attenuate the effects induced by F.