The influence of fluoride administration on the structure of proteoglycans in the developing rat incisor.

1. 35S-labelled chondroitin 4-sulphate proteoglycan was isolated from the mineralized elements of the developing incisor teeth of Harvard rats receiving intraperitoneal administration of Na235SO4. 2. The chondroitin 4-sulphate proteoglycan underwent a decrease in molecular size in fluorotic teeth as judged by gel filtration on Sepharose 2B. 3. When examined by anion-exchange chromatography on DEAE cellulose-52, the proteoglycan from fluorotic teeth resolved into four peaks in comparison with the material from non-fluorotic teeth, which exhibited only a single major peak. 4. Both the single peak from non-fluoridated teeth and the four peaks from the fluorotic teeth were further resolved on cellulose acetate electrophoresis. 5. Isolated chondroitin 4-sulphate chains obtained from fluorotic teeth also were of smaller molecular size as judged by gel filtration on Sephadex G-150. 6. Some possible influences of fluoride on the metabolism of these connective-tissue components in the developing rat incisor are discussed.