Abstract
Abstract
Two methods of administering fatty acids to cells in culture were compared for their effects on growth, phospholipid acyl group composition, and triacylglycerol formation. Solutions of fatty acid salts were delivered to suspension cultures of L fibroblasts either by infusion at a constant rate over 48 hr, or an amount of fatty acid equal to that infused was added as a single dose complexed to albumin at the start of the 48-hr incubation period. With an initial cell density of 2.5 × 105/ml, 5-18 μmole of Na oleate could be delivered by either method with no adverse effects on the cells. Linoleate (18:2) at the high end of this range, however, decreased culture growth by as much as 50% when the infusion method was employed and 15% when the fatty acid was added as a single dose. At low doses, 5 μmole, 18:2 had little effect on the growth rate. Over a 48-hr period infusion of 5 μmole of 18:2 caused the dienoic acyl group content of phospholipid to increase 22-fold, while the single-dose method increased it by a factor of 18. Time-course studies showed that the triacylglycerol content in the latter case increased to max levels from the 6th to the 24th hr at least 60 times greater than that of control cells not supplemented with fatty acid. The max increase in triacylglycerol above control levels during infusion of 18:2 was only 8-fold and occurred at 24 hr. The infusion method at low levels of 18:2 is at least as effective as the single-dose method in modifying phospholipid acyl group composition, but had the advantage of maintaining lower levels of triacylglycerol.
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