Fig. 3.

Labeling studies indicate diverse mechanisms for PAL-induced ceramide production. C2C12 myotubes were treated with 1.25 mM uniformly labeled ¹³C- PAL with or without 0.1 μM myriocin. After 14 h treatment, the lipid fraction was extracted from cell pellets and subjected to LC/MS analysis. The label became incorporated in the dihydrosphingosine backbone (base) (A), in the N-acyl chain (B), in both chains of ceramide (dual) (C), or in neither chain of ceramide (neither) (D). Data are expressed as means (n = 3) ± SEM. For all N-acyl chain lengths and for total ceramide, CTL versus PAL, P < 0.05; PAL-MY versus PAL, P < 0.05. CTL, control; MY, myriocin. FA, N-acyl chain.