Ceramide is a lipid second messenger that acts on mul-tiple-target enzymes, some of which are involved in other signal-transduction systems. We have previously demon-strated that endogenous ceramide modifies the metabolism of brain ethanolamine plasmalogens. The mechanism involved was studied. On the basis of measurements of breakdown products, specific inhibitor effects, and previ-ous findings, we suggest that a plasmalogen-selective phospholipase A2 is the ceramide target.
