M. Moreno et al., KINETIC CONSTANTS OF ALPHA-METHYL-D-GLUCOSIDE TRANSPORT IN THE CHICK SMALL-INTESTINE DURING PERINATAL-DEVELOPMENT, Mechanism of ageing and development, 92(1), 1996, pp. 11-20
The kinetic parameters of alpha-methyl-D-glucoside (alpha GlclMe) have
been determined in the small intestine in order to establish developm
ental and regional changes in the apical transport in embryos and newl
y hatched chicks. Results show that the apparent Michaelis constant (K
-m) values did not change during the period studied in each region of
the small intestine. However, the ileum showed a smaller K-m than that
of the duodenum and jejunum, indicating an increase of the affinity o
f the carrier in the distal portion of the intestine and a significant
contribution of the ileum to overall sugar absorption in the perinata
l period. There were important changes in the diffusional component an
d in the mediated transport system capacity during this period, as wel
l as in the different regions of the intestine. Significant increases
in the maximal rate of transport (V-max) were observed in all regions
during the embryonic period until the second day after hatching, follo
wed by a decline during the first week. During all the period studied,
V-max values from the jejunum were significantly greater than those f
rom both the duodenum and the ileum at every age studied showing that
the jejunum is the segment that is best suited for Na+-mediated uptake
. Such changes which occur when the need for nutrients for rapid devel
opment are at their highest are not solely a result of diet compositio
n, but rather in accordance with a genetic programme. Copyright (C) 19
96 Elsevier Science Ireland Ltd.