AJP - Gastrointestinal and Liver Physiology, Vol 249, Issue 3 328-G334, Copyright © 1985 by American Physiological Society
Age-related changes in rat intestinal transport of D-glucose, sodium, and water
G. Esposito, A. Faelli, M. Tosco, M. N. Orsenigo and R. Battistessa
Experiments were performed with everted sacs of jejunum and ileum and
brush-border membrane vesicles from four different age groups of rats: very
young, young, adult, and old. The changes with age in several parameters,
such as cell electrolyte and D-glucose concentrations, cell volume, net
D-glucose, Na+ and water transport, and D-glucose uptake into vesicles,
were studied. Differences in transport activities in the four age groups of
animals were observed. In the jejunum the greatest transport was found in
young rats and less in adult, very young, and old rats. In the ileum, the
greatest transport activity was found in very young and young rats, while
in adult and old animals transport activity was negligible. The cell volume
of the enterocyte was significantly smaller in old rats. Changes in cell
electrolytes (increased Na+ and decreased K+) were observed only in the
jejunum of old rats. The overshoot of D-glucose in brush-border membrane
vesicles varied considerably in the four different age groups of animals.
In other words, the capacity for sugar uptake into vesicles is greater in
young rats than in very young or adult animals. In old rats there was no
overshoot, and a slow linear increase of sugar entry was observed. The
results indicate that the changes in D-glucose transport with age might be
explained in part by the changes in the amount of sugar that crosses the
brush-border membrane of the enterocyte.
