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Kinetic constants of alpha-methyl-D-glucoside transport in the chick small intestine during perinatal development
1Departament de Biologia Fonamental i Ciencies de la Salut, Universitat de les Illes Balears, Palma de Mallorca (Balears), Spain.
Insights
This study reveals that the ileum has a higher affinity for sugar absorption in developing chicks, while the jejunum shows the greatest capacity for nutrient uptake. These changes are part of a genetic program for rapid development.
Area of Science:
- Animal Physiology
- Gastrointestinal Physiology
- Developmental Biology
Background:
- Apical sugar transport in the small intestine is crucial for nutrient absorption in developing animals.
- Understanding developmental and regional changes in nutrient transport is key to optimizing chick growth and health.
Purpose of the Study:
- To determine the kinetic parameters of alpha-methyl-D-glucoside (alpha Glc1Me) transport in the small intestine of chick embryos and newly hatched chicks.
- To establish developmental and regional variations in apical sugar uptake.
- To elucidate the contribution of different intestinal segments to overall sugar absorption during the perinatal period.
Main Methods:
- Determination of kinetic parameters (apparent Michaelis constant (Km) and maximal transport rate (Vmax)) for alpha-methyl-D-glucoside (alpha Glc1Me) transport.
- Analysis of regional differences (duodenum, jejunum, ileum) in the small intestine.
- Assessment of developmental changes from embryonic stages to the first week post-hatching.
Main Results:
- Apparent Michaelis constant (Km) values remained stable regionally but were lower in the ileum, indicating higher carrier affinity in the distal intestine.
- Maximal transport rate (Vmax) increased significantly from embryonic stages to day two post-hatching, then declined during the first week.
- The jejunum exhibited significantly higher Vmax values than the duodenum and ileum across all ages, suggesting it is the primary site for Na(+)-mediated uptake.
Conclusions:
- The ileum plays a significant role in perinatal sugar absorption due to increased carrier affinity.
- The jejunum is the most efficient segment for Na(+)-mediated nutrient uptake in developing chicks.
- Observed changes in nutrient transport are regulated by a genetic program to meet the high demands of rapid development, independent of diet composition.
Abstract:
The kinetic parameters of alpha-methyl-D-glucoside (alpha Glc1Me) have been determined in the small intestine in order to establish developmental and regional changes in the apical transport in embryos and newly hatched chicks. Results show that the apparent Michaelis constant (Km) values did not change during the period studied in each region of the small intestine. However, the ileum showed a smaller Km than that of the duodenum and jejunum, indicating an increase of the affinity of the carrier in the distal portion of the intestine and a significant contribution of the ileum to overall sugar absorption in the perinatal period. There were important changes in the diffusional component and in the mediated transport system capacity during this period, as well as in the different regions of the intestine. Significant increases in the maximal rate of transport (Vmax) were observed in all regions during the embryonic period until the second day after hatching, followed by a decline during the first week. During all the period studied, Vmax values from the jejunum were significantly greater than those from 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 development are at their highest are not solely a result of diet composition, but rather in accordance with a genetic programme.