Recently,
in our experiments, we used the short-circuit
current technique to study the kinetic constants for nutrient
transporters in rat gastric-intestinal tract and the thickness of the intestinal
unstirred layer near the mucosa surface. It was shown that, during the process of aging, the number of nutrient monomer transporters in the small intestine
increases twofold, whereas the affinity of transporters to the correspondent
nutrients remains unchanged. The situation for peptides may be opposite. The
layer thickness in the vicinity of the mucosa surface, measured through
glucose, decreased during the process of aging. It was suggested that, in old
rats, the role of the digestive volume is more important, which results in an increase of the number of nutrient monomer transporters.
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