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In vivo intestinal calcium transport in infant rats: normal and growth retarded
Insights
Intestinal calcium transport changes during rat maturation. Protein-deficient diets impacted calcium absorption differently in young versus older rats, suggesting developmental changes in transport mechanisms.
Area of Science:
- Physiology
- Developmental Biology
- Nutritional Science
Background:
- Intestinal calcium absorption is crucial for bone health and development.
- Understanding age-related changes in calcium transport is vital for pediatric nutrition and growth studies.
Purpose of the Study:
- To investigate the in vivo transport of calcium (Ca) in the jejunum and ileum of rats at different developmental stages (1-6 weeks).
- To assess the impact of maternal protein deficiency on calcium absorption during rat maturation.
Main Methods:
- Comparison of net absorption and bidirectional calcium fluxes (lumen-to-mucosa and mucosa-to-lumen) in the jejunum + ileum of rats aged 1, 2, 3, 4, and 6 weeks.
- Evaluation of calcium transport in rats born to mothers fed a protein-deficient diet versus control diet.
Main Results:
- In normal rats, net Ca absorption and fluxes were similar in 1-3 week olds and significantly lower in 6-week olds.
- Growth retardation due to maternal protein deficiency suppressed Ca absorption in 4- and 6-week old rats.
- Conversely, protein deficiency slightly enhanced Ca absorption in 1-3 week old rats.
Conclusions:
- Intestinal calcium transport mechanisms undergo significant changes during rat maturation.
- Maternal protein deficiency differentially affects calcium absorption based on the age of the offspring, highlighting developmental sensitivity.
- Body weight gain did not correlate with net calcium absorption rates in the jejunum + ileum.
Abstract:
We compared the in vivo transport of calcium (Ca) in the jejunum + ileum of 1-, 2-, 3-, 4-, and 6-week old rats. In normal rats, net absorption and the estimated bidirectional fluxes of Ca (lumen-to mucosa and mucosa-to-lumen) normalized for differences in size of the intestine (mumoles/hour per g weight) were similar in the 1-, 2-, and 3-week old rats and significantly lower in the 6-week old than in the younger rats. Growth retardation (pups raised with mothers fed a diet deficient in protein) appeared to have suppressed net absorption and the bidirectional fluxes of calcium in the 4- and 6-week old rats, but to have slightly enhanced net absorption and the bidirectional fluxes in the 1-, 2-, and 3-week old rats. These findings suggested a change in the mechanism(s) for intestinal transport of Ca during maturation. Rate of gain in body weight expressed as g/day increased with age from 1.4 g/day between 1 and 2 weeks, to 6.1 g/day between 4 and 6 weeks of age. There was no correlation between rate of net Ca absorption from the jejunum + ileum and gain in body weight expressed as g/day or as percent per day.