| Abstrakt: |
Extract: The small intestinal mucosal phase of fatty acid absorption was studied in suckling and adult rats. Fatty acid binding protein (FABP) is present in the cytosol of jejunal mucosa of 6-day-old rats in amounts equivalent to that found in mucosal cytosol of adult rats (16.4% and 15.0%, respectively). The percentage of oleic acid binding to FABP is the same in 6-day-old and adult rats (13.9% and 10.2%, respectively). The specific activity of jejunal microsomal oleoyl-CoA synthetase is high in the fetus, falls abruptly after birth, but increased by the third day of life to remain constant thereafter into adult life. In contrast the specific activity of acyl-CoA:monoglyceride acyltransferase is low in the fetal jejunum, gradually increases, and is significantly higher in the 6- and 12-day-old rat than in the adult. Uptake of oleic acid by jejunal slices of 6-and 11-day-old animals is three- to fivefold higher than uptake by jejunal slices prepared from adults rats. The rate of esterification of oleic acid is higher in jejunal slices from 6- and 11-day-old rats, reflecting the enhanced uptake of oleic acid.Speculation: In the suckling rat, the increased intestinal mucosal epithelial cell capacity for fatty acid esterification coincides with a diminished lipolytic activity within the lumen. This paradox suggests that the fatty acid esterification process in the small intestine of the suckling rat may be involved with aspects of lipid metabolism other than that of fatty acid absorption. Extrapolating these observations on experimental animals to the human neonate, we suggest as working hypothesis that inefficient fat absorption should not be attributed to diminished mucosal epithelial cell function. |
