In vitro turnover of oleate and arachidonate in lipids of Discopyge tschudii electrocyte membranes

1. 1. The incorporation and distribution of two unsaturated fatty acids, [³H]arachidonate and [³H]oleate, into lipids of living electrocytes was studied in Discopyge tschudii (Torpedinidae) in vitro. 2. 2. Thirty and 40% of the label was found in phospholipids and neutral lipids respectively, triacylglycerols accumulating the greater part. In terms of lipid mass, polyphosphoinositides displayed the highest turnover of both fatty acids. In general, oleate turnover was faster than that of arachidonate. 3. 3. Fatty acid turnover appears to be an active process in the electrocyte, deacylation-reacylation processes dominating acyl group metabolism. Enzymes catalysing these reactions may play important functions in the control of physical properties in excitable membranes.