Postnatal development of nutrient transport in the intestine of dogs.
OBJECTIVE
To measure nutrient absorption by the intestine during postnatal development of dogs.


METHODS
110 Beagles ranging from neonatal to adult dogs.


METHODS
Rates of absorption for sugars (glucose, galactose, and fructose), amino acids (aspartate, leucine, lysine, methionine, and proline), a dipeptide (glycyl-sarcosine), and linoleic acid by the proximal, mid, and distal regions of the small intestine were measured as functions of age and concentration (kinetics) by use of intact tissues and brush-border membrane vesicles. Absorption of octanoic acid by the proximal portion of the colon was measured in intact tissues.


RESULTS
Rates of carrier-mediated transport by intact tissues decreased from birth to adulthood for aldohexoses and most amino acids but not for fructose and aspartate. Kinetics and characteristics of absorption suggest that there were changes in the densities, types, and proportions of various carriers for sugars and amino acids. Saturable absorption of linoleic acid in the small intestine and octanoic acid in the proximal portion of the colon increased after weaning.


CONCLUSIONS
Rates of absorption decreased between birth and adulthood for most nutrients. However, because of intestinal growth, absorption capacities of the entire small intestine remained constant for leucine and proline and increased for glucose, galactose, fructose, aspartate, and proline but were less than predicted from the increase in body weight. Although postnatal ontogeny of nutrient absorption was consistent with changes in the composition of the natural and commercial diets of growing dogs, rates of amino acid and peptide absorption were lower than expected.
Buddington
Randal K
RK
Department of Biological Sciences, College of Arts and Science, Mississippi State University, Mississippi State, MS 39762, USA.
Malo
Christiane
C
D000042:Absorption; D000375:Aging / Q000502:physiology*; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000833:Animals, Suckling; D001692:Biological Transport; D050260:Carbohydrate Metabolism; D004151:Dipeptides / Q000378:metabolism; D004285:Dogs / Q000254:growth & development* / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000254:growth & development / Q000378:metabolism; D007421:Intestine, Small / Q000254:growth & development* / Q000378:metabolism*; D007700:Kinetics; D019787:Linoleic Acid / Q000378:metabolism; D008297:Male; D008871:Microvilli / Q000378:metabolism
D000596:Amino Acids; D004151:Dipeptides; C004194:glycylsarcosine; D019787:Linoleic Acid