Postnatal development of glucose transport in the proximal small intestine of the rabbit.

Developmental change in intestinal solute transport was examined by studying glucose transport in rabbit jejunal tissue at age intervals after birth. Net D-glucose absorption was greater in jejunum from suckling rabbits (10-14 days old) compared to older animals when studied in Ussing-type short-circuited chambers, and jejunal tissue slices from these younger animals accumulated more intracellular D-glucose. Net fluxes of 3-0-methyl-D-glucose were also greater in jejunum from the younger age group, excluding this effect being due to substrate metabolism. Increased permeability of jejunal epithelium in immature animals was evidenced by larger unidirectional fluxes and higher conductance. The findings suggest that the developing jejunum, although more permeable, has an increased capacity for active sugar transport, a pattern differing from that seen with most other intestinal absorptive functions.