Glucose absorption in House sparrow nestlings does not depend on age or diet

BRZEK, P.; CAVIEDES-VIDAL, E.; KARASOV, W.H.

Seattle WA USA

Congreso; Society for Integrative Comparative and Biology; 2010

Society for Integrative Comparative and Biology

Young birds show great age-related changes in functional maturity of their gastrointestinal tract. However, little is known about development of nutrient absorption in birds, or the physiological background of diet shifting. In nestling House sparrows (Passer domesticus) we studied the effect of age and diet on the fractional absorption (f) of 3-O-methyl-D-glucose (3OMG), a non-metabolizable D-glucose analogue absorbed actively and passively. Wild nestlings removed from nests were fed or injected with the radiolabeled compound and serially blood sampled over several hours, and f was calculated as the quotient of areas under the curve of 3OMG concentration in blood plasma vs time. Nestlings aged 6- and 12-d post hatch absorbed a similar fraction of ingested 3OMG as did adults in our earlier published study (J. Exp. Biol. 207:3109-3121, 2004). By comparing these results with preliminary measures using L-glucose (another non metabolizable analogue of D-glucose but not actively transported), we conclude that most absorption is passive, as found previously in adults. Four-, 6-, and 12-d old nestlings raised in the laboratory and hand fed diet with or without starch, and also containing radiolabeled 3OMG, had similar radiolabel values in plasma, indicating that habituation to dietary carbohydrate has no significant effect on fractional 3OMG absorption.