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Membrane fluidity and lipid composition of rat small intestinal brush-border membranes during postnatal maturation
C Hübner1, S G Lindner, M Stern
1Department of Pediatrics, University of Hamburg, F.R.G.
Insights
Rat small intestinal brush-border membranes (BBM) show significant changes in fluidity and lipid composition during maturation. These findings enhance understanding of how biophysical and biochemical properties correlate in developing biological membranes.
Area of Science:
- Membrane Biology
- Biochemistry
- Physiology
Background:
- Rat small intestinal brush-border membranes (BBM) undergo developmental changes.
- Understanding these changes is crucial for comprehending nutrient absorption and membrane function.
Purpose of the Study:
- To investigate maturational changes in fluidity and lipid composition of rat BBM.
- To correlate biophysical and biochemical data during BBM development.
Main Methods:
- Studied five age groups of rats: newborns, sucklings, weaned, juveniles, and adults.
- Measured BBM fluidity using steady-state fluorescence polarization with specific fluorescent probes.
- Analyzed lipid composition, including fatty acid ratios and cholesterol-to-phospholipid and cholesterol-to-protein ratios.
Main Results:
- Increased fluorescence anisotropy in adult versus newborn rats indicates reduced membrane fluidity with age.
- The ratio of saturated to cis-unsaturated fatty acids increased from birth to suckling age.
- Cholesterol-to-phospholipid ratio increased until the weaned stage, while cholesterol-to-protein and phospholipid-to-protein ratios decreased post-weaning.
Conclusions:
- Maturational changes in rat BBM involve significant alterations in membrane fluidity and lipid composition.
- The study provides insights into the relationship between the biophysical properties (fluidity) and biochemical composition (lipids, proteins) of BBM during development.
Abstract:
Fluidity and lipid composition of rat small intestinal brush-border membranes (BBM) were studied during maturation in five age groups: newborns, sucklings (1-3 weeks), weaned (4-6 weeks), juveniles (8-10 weeks), and adults (12 weeks). Brush-border membrane fluidity was measured by steady-state fluorescence polarization. Fluorescent probes used were: 1,6-diphenyl-1,3,5-hexatriene, 1-(4-trimethylammonium)phenyl)-6-phenyl-1,3,5-hexatriene, and a set of n-(9-anthroyloxy) fatty acids. Fluorescence anisotropy measured with all fluorophores was increased in adult versus newborn rats (P less than 0.004). The weight ratio of saturated to cis-unsaturated fatty acids increased from birth to the suckling age (P less than 0.0004). The cholesterol to phospholipid molar ratio increased from birth to the weaned age (P less than 0.0001). Cholesterol to protein ratio and phospholipid to protein ratio decreased after the weaned age (P less than 0.004). The results not only describe maturational changes of brush-border membranes but also give a better understanding of the correlations between biophysical and biochemical data in biological membranes.