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Development maturation of riboflavin intestinal transport in the rat
Insights
Intestinal riboflavin transport matures with age in rats, showing decreased affinity and carrier activity in adults. This process relies on energy, temperature, and sodium, indicating a carrier-mediated mechanism throughout development.
Area of Science:
- Gastroenterology
- Nutritional Science
- Developmental Biology
Background:
- Riboflavin (vitamin B2) is essential for numerous metabolic processes.
- Understanding its intestinal absorption is crucial for nutritional science.
- Intestinal development significantly impacts nutrient transport dynamics.
Purpose of the Study:
- To investigate the maturation of intestinal riboflavin transport in rats.
- To compare riboflavin transport rates and kinetics across different age groups.
- To elucidate the characteristics of the riboflavin transport system during intestinal development.
Main Methods:
- Utilized the everted sac technique to study intestinal transport.
- Measured mucosal-to-serosal transport of riboflavin in suckling, weanling, and adult rats.
- Analyzed kinetic parameters including affinity (Kt) and maximal transport rate (Vmax).
Main Results:
- Riboflavin transport rate decreased with age (4.6, 3.6, 1.6 pmol/g/min in suckling, weanling, adult rats).
- Transport was higher in the jejunum than ileum across all age groups.
- The transport system was saturable, energy-, temperature-, and Na+-dependent, indicating carrier-mediated transport.
Conclusions:
- Intestinal riboflavin transport occurs via a carrier-mediated process dependent on energy, temperature, and sodium.
- While the transport mechanism remains consistent, its affinity and carrier activity decrease with intestinal maturation.
- These findings highlight age-related changes in vitamin B2 absorption efficiency.
Abstract:
The intestinal transport of riboflavin in the immature intestine of the suckling rat (14 day old) and its subsequent maturation in weanling (22 day old) and adult (90 day old) rats were investigated using the intestinal everted sac technique. The mucosal-to-serosal transport of 0.5 microM riboflavin was linear with time for 30-min incubation and occurred at a rate of 4.6, 3.6, and 1.6 pmol/g initial tissue wet wt/min in suckling, weanling, and adult rats, respectively. The transport of 0.5 microM riboflavin was higher in the jejunum than the ileum in all age groups. The transport system of riboflavin in all age groups was saturable, energy-, temperature-, and Na+-dependent. Kinetic parameters of the transport process were different. Apparent Kt of the transport process was the same in suckling and weanling rats (0.12 and 0.11 microM, respectively) but tripled in adult rats (0.35 microM). On the other hand, a progressive decrease in Vmax from 166 to 122 to 54 pmol/g initial tissue wet weight/30 min was observed in the suckling, weanling, and adult rats, respectively. The present study demonstrates that the characteristics of the transport process of riboflavin is similar in suckling, weanling, and adult rats and occurs by an energy-, temperature-, and Na+-dependent carrier-mediated process. However, the affinity and the activity (or the number) of the transport carriers of riboflavin decrease with maturation.