Formation of ceramide in ethanol-treated astrocytes: concentration dependence. Astrocytes were labeled with 3H-serine for 72 hours, washed and treated with ethanol (0.1–1 %, v/v). After (A) 1 hour and (B) 18 hours, the cells were extracted with methanol/chloroform (2:1), phospholipids were separated by TLC, and the radioactivity associated with ceramide and sphingomyelin was determined by liquid scintillation counting. Data (N = 5–6) are means ± S.E.M. and are expressed as [%] ceramide/sphingomyelin. Statistics: one-way ANOVA for repeated measurements, (A) F3,19 = 3.98, p = 0.03; (B) F3,23 = 4.88, p = 0.02. *, p < 0.05 vs. controls (Dunnett's post test).