Effect of exogenous fatty acids on the retention of phospholipid acyl groups by mouse L fibroblasts

Abstract

Exogenous oleic or linoleic acid, given at a high but nontoxic level (1 mg fatty acid/day for 20 · 10 6 cells in 50 ml medium), caused substantial redistribution of the otherwise permanently retained phospholipid acyls in mouse L fibroblasts. 18–40% of the preformed phospholipid acyls were shifted to triglycerides but most returned to phospholipids when the supply of exogenous fatty acid was removed. The phospholipid acyls could be reshuttled back to triglycerides again whenever an adequate amount of exogenous fatty acid was provided. Daily changes of medium containing oleic acid bound to bovine serum albumin caused a still greater total loss of phospholipid acyls into the medium. The removal of the prelabeled phospholipid acyls also occurred with phospholipid acyls which had been synthesized from [1- 14C]acetate 3 days earlier. The results demonstrate the fact that the apparent permanently retained phospholipid acyl groups found in L-cells could in fact be displaced through experimental manipulations.