MODIFICATION OF MEMBRANE FATTY-ACID COMPOSITION, EICOSANOID PRODUCTION, AND PHOSPHOLIPASE-A ACTIVITY IN ATLANTIC SALMON (SALMO-SALAR) GILL AND KIDNEY BY DIETARY-LIPID

Atlantic salmon post-smelts were fed diets containing either fish oils (Fosol, FO and Marinol, MO) rich in long-chain n-3 polyunsaturated fa tty acids (PUFA), or plant oils rich in 18:2n-6 (sunflower oil, SO) or 18:3n-3 (linseed oil, LO) for 12 wk. The major PUFA in individual pho spholipids from gill and kidney were related to the dietary lipid inta ke. Levels of n-6 PUFA were highest while levels of n-3 PUFA were lowe st in fish fed SO. Fish fed LO generally had lower levels of 20:4n-6 c ompared to the other treatments while fish fed SO generally had the hi ghest levels of 20:4n-6. In all phospholipid classes except phosphatid ylinositol (PI) 20:5n-3 was greatest in fish fed MO followed by FO, LO , and SO. In PI, 20:5n-3 was also highest in fish fed MO but those fed LO contained more 20:5n-3 than those fed FO. This resulted in the rat io of the eicosanoid precursors, 20:4n-6/20:5n-3, being significantly greater in fish fed SO, for all phospholipid classes, compared to fish fed the other three dietary oils. The activity of gill phospholipase A was greatest in fish fed FO and was lowest in fish fed SO. The conce ntration of PGF(3 alpha) was significantly increased in gill homogenat es from fish red MO compared to the other three treatments while PGF(2 alpha) was significantly increased in fish fed SO compared to PCF tho se fed LO. The concentration of PGE(3) was significantly reduced in ki dney homogenates from fish fed SO compared to the other three treatmen ts while PGE(2) was significantly increased in fish fed SO compared to those fed either FO or LO.