Glucose and amino acid absorption in house sparrow intestine and
its dietary modulation.
Caviedes-Vidal, Enrique, and William H. Karasov.
Department of Wildlife Ecology, University of Wisconsin, Madison,
WI 53706, USA, Departamento de Bioqu[acute]imica y Ciencias
Biol[acute]ogicas. Universidad Nacional de San Luis, CC226, 5700 San
Luis, Argentina
APStracts 3:0077R, 1996.
We acclimated House Sparrows (Passer domesticus; 26 g) to high starch
(HS), high protein (HP) and high lipid (HL) diets and tested the
predictions that uptake of D-glucose and amino acids will be
increased with increased levels of dietary carbohydrate and protein,
respectively. HS birds had lower mediated D-glucose uptake rate than
HP birds. Total uptake of L-leucine at low concentration (0.01 mM),
but not of L-proline at 50 mM, was increased by dietary protein.
Measures of D-glucose maximal mediated uptake (1.2 + 0.2 nmol min-1
mg-1) and intestinal mass (1 g) indicated that the intestine's
mediated uptake capacity was only 10% of the D-glucose absorbed at
the whole-animal level. This implied that nonmediated glucose
absorption predominated. We applied a pharmacokinetic technique to
measure in vivo absorption of L-glucose, the stereoisomer that does
not interact with the Na+/glucose cotransporter. At least 75% of L
-glucose that was ingested was apparently absorbed. This adds to the
increasing evidence that substantial passive glucose absorption
occurs in birds, and may explain why mediated D-glucose uptake does
not increase on high carboydrate diets.
Received 3 August 1995; accepted in final form 1 March 1996.
APS Manuscript Number R491-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96