Effect of age-dependent changes on jejunal and ileal amino acid-sugar interaction in vivo.

The effects of L-leucine on jejunal and ileal D-galactose absorption have been studied at three different ages in rats using a perfusion system in vivo. Both, D-galactose and L-leucine have been perfused through the jejunum and the ileum at two concentrations, 5mM (low) and 20 mM (high). L-leucine induced a reversible inhibition of D-galactose absorption at the three ages studied and in both intestinal segments. The inhibition was higher at 20 mM when carriers were saturated. A lineal correlation exits between the inhibition percentage and the age of animals, increasing with growth in the jejunum and decreasing in the ileum. Attention is called to the possibility of different transport mechanisms at low concentration (5 mM), one of low affinity in the jejunum and the other of high affinity in the ileum.