Fig 2. Lipolysis and re-esterification of oleic acid in myotubes after co-incubation with fatty acids.

Human myotubes were grown and differentiated in 96-well ScintiPlate tissue culture plates. On day 6 of differentiation the myotubes were treated with a mixture of 100 μM fatty acids for 24 h. The mixture was trace amounts of [¹⁴C]OA (9 μM) and non-labeled PA or EPA (20:5, n-3) (91 μM). (A) Total lipolysis (lipolysis measured in presence triacsin C, 10 μM) of cell-associated [¹⁴C]OA at 1, 2, 4, and 6 h after 24 h pretreatment. (B) Total lipolysis presented as relative decline (i.e. data normalized to cell-associated radioactivity at zero time) in cell-associated [¹⁴C]OA at 1, 2, 4, and 6 h after 24 h pretreatment. (C) Re-esterification of [¹⁴C]OA, calculated as the difference between lipolysis measured at 1, 2, 4, and 6 h by SPA in the presence or absence of triacsin C (10 μM). Results represent mean ± SEM as nmol/mg protein (A, C) and relative decline in cell-associated radioactivity (B) for n = 3 donors. Significant increased lipolysis, decline and re-esterification for EPA vs. PA. p<0.05 for EPA vs. PA (all-over effect), LMM statistical test (SPSS). EPA, eicosapentaenoic acid; PA, palmitic acid; SPA, scintillation proximity assay; LMM, linear mixed model.