Figure 6.

Effect of PGC-1 on intracellular lipid flux and synthesis after incubation with [¹³C]glucose or [¹³C]stearate (18:0). C2C12 myotubes were incubated at 24 h postinfection with 5 mM glucose-5 mM [d-1,2-¹³C₂]glucose (A–C) or 1% BSA-125 μM [¹³C]stearic acid (D–F) in DMEM-H, with 2% HS for 72 h. A–C) Relative contents of fatty acids (A), ceramides (B), and sphingomyelins (C) were determined by SIDMAP and GC/MS. D) ¹³C incorporation into glutamate (MZ198) was measured as an indicator of TCA cycle flux. E) Synthesis of C18 by chain shortening and elongation from [¹³C]stearate. F) Synthesis of C20, C22, and C24 by chain elongation from [¹³C]stearate (C18). Values are means ± se. Values are expressed relative to GFP-infected cells in panels D–F. *P < 0.05; **P < 0.01; ***P < 0.001. Note that some error bars are too small to be visualized.