Cultures of rat cortical neurons, prelabeled with [³H]ethanolamine, were incubated for 10 min in DMEM with or without BTNP (25 μm), and then incubated for additional 10 min with ionomycin (1 μm) and BTNP, as indicated. N-[³H]acyl PE were purified by monodimensional TLC and quantified by liquid scintillation counting. Results are from one experiment performed in four separate cultures, repeated once with identical results.