Intestinal transport of monosaccharides and amino acids during postnatal development of mink

Intestinal development is typically studied using omnivores. For comparativ e purposes, we examined an altricial carnivore, the mink (Mustela vison). I n mink, intestinal dimensions increase up to 8 wk after birth and then rema in constant (length) or decrease (mass) into maturity despite continuing ga ins in body mass. Rates of glucose and fructose transport decline after bir th for intact tissues but increase for brush-border membrane vesicles (BBMV ). Rates of absorption for five amino acids that are substrates for the aci dic (aspartate), basic (lysine), neutral (leucine and methionine), and imin o acid (proline) carriers increase between birth and 24 h for intact tissue s before declining, but increase after 2 wk for BBMV. The proportion of BBM V amino acid uptake that is Na+-dependent increases during development but for aspartate is nearly 100% at all ages. Tracer uptake by BBMV can be inhi bited by 100 mmol/l of unlabeled amino acid, except for lysine. BBMV uptake of the dipeptide glycyl-sarcosine does not differ between ages, is not Na dependent, and is only partially inhibited by 100 mmol/l unlabeled dipepti de. Despite the ability to rapidly and efficiently digest high dietary load s of protein, rates of amino acid and peptide absorption are not markedly h igher than those of other mammals.