Fig. 1.

Biosynthesis of [³H]NAPE in primary cultures of rat brain cortical neurons. a, Ionomycin (1 μm, 10 min) stimulates [³H]NAPE biosynthesis in neurons labeled by incubation with [³H]ethanolamine (Eth), [³H]arachidonic acid (AA), or [³H]palmitic acid (PA). NAPE was fractionated by column chromatography, and NAPE-containing fractions were analyzed by monodimensional TLC. Results are expressed as mean ± SEM (dpm/dish) of six separate experiments.b, The effect of ionomycin is prevented by chelating extracellular Ca²⁺ with EGTA (10 mm) and is concentration-dependent (inset, μm concentrations). In these experiments, the neurons were labeled with [³H]ethanolamine. c, d, Ionomycin stimulates NAPE biosynthesis in neurons (c), but not in astrocytes (d). Cultures were labeled by overnight incubation with [¹⁴C]arachidonic acid. NAPE was analyzed by bidimensional TLC and autoradiography. On these representative chromatograms, the numbers indicate the positions of the following lipids: (1) NAPE; (2) unknown; (3) cerebrosides; (4) PE; (5) PC; (6) phosphatidylserine plus phosphatidylinositol.O, Origin.