Kinetics of hexose uptake by the small and large intestine of the
chicken.
Amat, Concepci[acute]o, Juana M. Planas, Miquel Moret[acute]o.
Grup d'Absorci[acute]o Intestinal, Unitat de Fisiologia, Facultat
de Farm[grave]acia, Universitat de Barcelona, Av. Joan XXIII s/n, E
-08028 Barcelona, Spain
APStracts 3:0139R, 1996.
The kinetic parameters of hexose uptake by the small and large
intestine of the chicken have been determined in vitro. Rates of
initial influx of [alpha]-methyl-D-glucoside and L-glucose were
measured in everted sleeves of the duodenum, jejunum, ileum, proximal
cecum and rectum. Results show that (a) Vmax values for [alpha]
-methyl-D-glucoside show that the jejunum is the segment that is best
suited for Na+-mediated uptake. (b) The calculated apparent Km were
(in mmol/L): duodenum, 11.6; jejunum, 7,8; ileum, 3.5; proximal
cecum, 2.4; rectum, 7.1. This suggests that with the exception of the
rectum, the affinity of the carrier for [alpha]-methyl-D-glucoside
progressively increases in the distal direction. (c) Kd values
indicate that influx of hexoses by a passive mechanism in the
duodenum and proximal cecum is significantly higher than in the other
segments. (d) The sum of passive and mediated mechanisms confers to
the duodenum and jejunum a high capacity to absorb hexoses. The
ileum, proximal cecum and rectum have a quantitatively minor role
-albeit significant- in completing the absorptive function.
Received 14 July 1995; accepted in final form 2 April 1996.
APS Manuscript Number R430-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96