Intestinal brush-border membrane enzyme activities and transport functions during prenatal development of pigs.
Enzyme 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. gamma-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.
Buddington
R K
RK
Department of Biological Sciences, Mississippi State University, Mississippi State 39762-5759, USA.
Malo
C
C
D000818:Animals; D000831:Animals, Newborn; D001693:Biological Transport, Active; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D005947:Glucose / Q000378:metabolism*; D006593:Hexokinase / Q000378:metabolism; D006801:Humans; D007421:Intestine, Small / Q000196:embryology / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D043322:Lactase; D007930:Leucine / Q000378:metabolism; D008871:Microvilli / Q000201:enzymology / Q000378:metabolism; D009929:Organ Size; D011247:Pregnancy; D013393:Sucrase / Q000378:metabolism; D013552:Swine / Q000196:embryology; D013997:Time Factors; D001616:beta-Galactosidase / Q000378:metabolism; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D005723:gamma-Glutamyltransferase; D006593:Hexokinase; D043322:Lactase; D001616:beta-Galactosidase; D013393:Sucrase; D007930:Leucine; D005947:Glucose