Intestinal Brush-Border Membrane Enzyme Activities and Transport Functions during Prenatal Development of Pigs

    loading  Checking for direct PDF access through Ovid


SummaryEnzyme activities and rates of leucine and glucose uptake were measured using brush-border membrane vesicles prepared from the small intestine of 7-, 8-, 10-, and 12-week fetal (43, 49, 61, and 74% of gestation) and unsuckled, neonatal pigs. Lactase was detected in 7-week fetuses, with a large increase in activity between 10 weeks of gestation and birth. γ-Glutamyltranspeptidase activity was stable throughout gestation, whereas sucrase activity was not detected. Active L-leucine uptake was already present at 7 weeks of gestation, with an increasing distal-to-proximal gradient observed at birth. D-glucose uptake was low at 7 weeks, but by 8 weeks it exhibited a typical overshoot phenomenon and established a decreasing proximal-to-distal gradient by 12 weeks. D-glucose uptake at all ages was directly related to incubation temperature, but less so for 7- and 10-week fetuses. By 12 weeks strict Na+-dependency of D-glucose uptake was observed along the entire length of the small intestine. Kinetic analysis of Na+-D-glucose cotransport showed a shift from the presence of both high- and low- affinity systems at 8 weeks of gestation to a single high-affinity Michaelian component at birth. In light of similarities with human fetuses, the pig may be a valuable model for studying development of intestinal transport during gestation, particularly during the final trimester, when availability of human tissue is limited.

    loading  Loading Related Articles