Abstract
Although glycosuria is absent in the newborn rat, uptake of galactose and alpha-methyl-D-glucoside (AMG) a non-metabolized transport model for glucose by newborn cortical slices is known to be impaired. We have shown concentration-dependent active uptake of AMG by isolated renal tubules from the newborn Sprague-Dawley rat and have confirmed the validity of this in vitro uptake phenomenon by an in vivo demonstration of AMG uptake by the newborn kidney. A kinetic analysis of the entry phenomenon for AMG in the newborn tubule reveals two distinct membrane transport systems, only one of which is present in the adult tubule. Glucose was shown to competitively inhibit uptake on the shared, high-capacity system, with a Ki of 2 mM in both newborn and adult tubules. The low-capacity system in the newborn (Km = 0.533 mM) was not affected by either 10 mM fructose or complete anoxia, although both glucose and galactose (10 mM) exerted inhibition on uptake by this system.
These data suggest that the newborn rat shares a sugar-transport system with the adult, but is able to transport less on this carrier per unit time. This deficit is offset by the presence of an additional system with a very high affinity, not present in the adult. The net result is a relatively efficient transport of sugar, impervious to anoxic insult, which approximates that of an adult.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Roth, K., Hwang, SM. & Yudkoff, M. SUGAR TRANSPORT IN ISOLATED NEWBORN RAT RENAL TUBULES A POSSIBLE EXPLANATION FOR THE ABSENCE OF NEONATAL GLUCOSURIA. Pediatr Res 11, 556 (1977). https://doi.org/10.1203/00006450-197704000-01118
Issue Date:
DOI: https://doi.org/10.1203/00006450-197704000-01118