Biliary phospholipid secretion is not required for intestinal absorption and plasma status of linoleic acid in mice.

Biliary phospholipids have been hypothesized to be important for essential fatty acid homeostasis. We tested this hypothesis by investigating the intestinal absorption and the status of linoleic acid in mdr2 Pgp-deficient mice which secrete phospholipid-free bile. In mice homozygous (-/-) for disruption of the mdr2 gene and wild-type (+/+) mice, dietary linoleic acid absorption was determined by 72 h balance techniques. After enteral administration, [(13)C]-linoleic acid absorption was determined by measuring [(13)C]-linoleic acid concentrations in feces and in plasma. The status of linoleic acid was determined in plasma and in liver by calculating the molar percentage of linoleic acid and the triene:tetraene ratio. Although plasma concentration of [(13)C]-linoleic acid at 2 h after enteral administration was significantly lower in (-/-) compared to (+/+) mice (P</=0.05), net intestinal absorption of dietary linoleic acid or of [(13)C]-linoleic acid was similar in (+/+) and (-/-) mice. Molar percentage of linoleic acid and the triene:tetraene ratio were not different in whole plasma or in liver of (-/-) compared to (+/+) mice. Present data indicate that biliary phospholipids are involved in the rate of appearance in plasma of enterally administered linoleic acid, but are not required for net intestinal absorption or plasma status of linoleic acid.