Corneal sulfate incorporation during fasting in rats

Fasting is known to decrease sulfate incorporation as well as other growth functions in cartilage. The present study compared corneal sulfation in vivo and in vitro, with sulfation in cartilage of rats undergoing total food deprivation for 48 hours and refeeding for periods up to 28 days. Sulfate incorporation by cartilage decreased both in vivo and in vitro during the fast and recovered to normal values by 7 days of refeeding. Corneal sulfation increased in vivo during the fast. After 7 days of refeeding corneal sulfation in vivo dropped below the control value and remained below the control level. At later recovery periods corneal sulfation in vivo was normal. Corneal sulfation in vitro decreased during the fast. Normal cartilage showed a decrease in sulfate incorporation in vivo and in vitro with increasing age. Corneal sulfation in vitro followed this pattern, but corneal sulfation in vivo did not. We conclude that the effect of fasting on sulfate metabolism of corneal stroma is qualitatively different from that of cartilage.