Maintenance of sucrase activity in rat small intestine. Influence of diet and age.

The long-term maintenance and acute induction of sucrase activity were studied under a variety of defined dietary conditions during the adult life-span of the Sprague-Dawley rat. Rats were fed chow, 74% carbohydrate, 56% carbohydrate, or 22% carbohydrate diets, from 44 to 106 weeks of age. Sucrase specific activity was measured in enterocytes isolated from the proximal, middle, and distal small intestine at 52, 86, and 104 weeks of age. Sucrase specific activity was correlated with the carbohydrate content of the diet but not affected by age throughout the adult life-span. In a second experiment, the acute induction of sucrase following a 48-hr fast was studied in 58- and 116-week-old rats. The increase in sucrase specific activity following refeeding was not different in the adult and aged rats. The results suggest that the carbohydrate-digesting capacity of the small intestine enterocyte of the Sprague-Dawley rat is not impaired during the aging process.