Abstract
Extract: The metabolic properties of the increased rate of transport in the 2-day-old rat intestine as compared with adult rat intestine were investigated. The intracellular accumulation of 1 mM of a prototype neutral amino acid (L-leucine) and sugar (D-galactose) was measured at 5 min in the presence of inhibitors and after preincubation with inhibitors. The intestine of the 2-day-old rat was found to be similar to adult rat intestine in its response to Na+ dependence, sulfhydryl binders, and metabolic inhibitors under conditions of aerobiosis; however, the immature rat intestine exhibited an ability to actively accumulate amino acids to a much greater extent than adult tissue under anaerobic conditions. Transport was inhibited only 12% in the newborn intestine while adult intestine showed a 44% inhibition at initial velocities. This anaerobic transport was similarly Na+ dependent and sensitive to metabolic inhibitors.
These results indicate that the increased transport found in newborn animals may be partially energized by anerobic metabolism, but suggest that the requirement for the maintenance of an active influx of sodium is similar in both neonates and adults.
Speculation: Anaerobic metabolism may partially account for the increased transport in newborn rats. Future studies may reveal whether the rate of anaerobic transport decreases in a pattern similar to the overall decrease in transport observed in the neonatal rat with maturation.
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Ferdinandus, L., Fitzgerald, J. & Reiser, S. Metabolic Properties of Neonatal Transport. Pediatr Res 8, 884–889 (1974). https://doi.org/10.1203/00006450-197411000-00006
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DOI: https://doi.org/10.1203/00006450-197411000-00006