Age dependent changes on jejunal sugar absorption by rat in vivo.

Jejunal absorption of D-Glucose, D-Galactose and L-Arabinose was studied in 21-23 day, 2-3 month and 18 month-old rats for 5 minute periods using a perfusion technique. Sugar concentrations were: 2.5, 5, 10, 20 and 40 mM at each age. In some experiments phlorizin was used to determine the diffusional component of absorption. The saturation for D-Glucose was at 10 mM and 5 mM for D-Galactose. A reduction in the rate of total sugar absorption was observed with aging. Moreover, the active transport/simple diffusion ratio also decreases with age, specially at low substrate concentrations.