| Autor: |
Werner, Anniek, Havinga, Rick, Perton, Frank, Kuipers, Folkert, Verkade, Henkjan J. |
| Předmět: |
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| Zdroj: |
American Journal of Physiology: Gastrointestinal & Liver Physiology; Jun2006, Vol. 290, pG1177-G1185, 9p, 1 Diagram, 2 Charts, 5 Graphs |
| Abstrakt: |
Biliary phospholipids (PL) stimulate dietary fat absorption by facilitating intraluminal lipid solubilization and by providing surface components for chylomicron (CM) assembly. Impaired hepatic PL availability induces secretion of large very-low-density lipoproteins, but it is unclear whether CM size depends on biliary PL availability. Biliary PL secretion is absent in multidrug resistance protein 2-deficient (Mdr2-/-) mice, whereas it is strongly increased in essential fatty acid (EFA)-deficient mice. We investigated lymphatic CM size and composition in mice with absent (Mdr2-/-) or enhanced (EFA deficient) biliary PL secretion and in their respective controls under basal conditions and during enteral lipid administration. EFA deficiency was induced by feeding mice a high-fat, EFA-deficient diet for 8 wk. Lymph was collected by mesenteric lymph duct cannulation with or without intraduodenal lipid administration. Lymph was collected in 30-mm fractions for up to 4 h, and lymphatic lipoprotein size was determined by dynamic light-scattering techniques. Lymph Iipoprotein subfractions were isolated by ultracentrifugation, and lipid composition was measured. Lymphatic CMs were significantly larger in Mdr2-/- mice than in Mdr2+/+ controls either without (+50%) or with (+25%) enteral lipid administration, and molar core-surface ratios were increased [triglyceride (TG)-to-PL ratio: 4.4 ± 1.4 in Mdr2-/- mice vs. 2.7 ± 0.8 in Mdr2+/+ mice, P < 0.001]. In contrast, EFA-deficient mice secreted lipoproteins into lymph that were significantly smaller than in EFA-sufficient controls (173 ± 32 vs. 236 ± 47 nm), with correspondingly decreased core-surface ratios (TG-to-PL ratio: 3.0 ± 1.0 in EFA-deficient mice vs. 6.0 ± 1.9 in EFA-sufficient mice, P < 0.001). CM size increased during fat absorption in both EFA-deficient and EFA-sufficient mice, but the difference between the groups persisted. In conclusion, the present results strongly suggest that the availability of biliary PL is a major determinant of the size of intestinally produced lipoproteins both under basal conditions and during lipid absorption. Altered CM size may have physiological consequences for postprandial CM processing. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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