Alterations in ceramide in hyperglycemic and fatty acid supplemented macrophages

Abstract

Ceramides are an important lipid pool that is used to store carbon energy substrates under high nutrient conditions. In the present study we examined the incorporation of fatty acids into ceramides of macrophages in the presence of euglycemic and hyperglycemic conditions. RAW 264.7 mouse macrophages were treated with selected fatty acids including stable isotope labeled fatty acids, and ceramides were detected by ESI‐MS/MS. Palmitic acid was incorporated into both the N‐fatty acyl position as well as the sphingosine backbone of ceramide during incubations with > 200 μM fatty acid. Using stable isotope labeled palmitic acid, fatty acyl elongation products were observed in the N‐acyl position. In comparison to stable isotope labeled palmitic acid, relatively less stable isotope labeled myristic acid was incorporated as elongated fatty acids into the ceramide pool. Palmitic acid elongation products were incorporated into ceramide at enhanced rates in the presence of high glucose. These studies revealed that not only are fatty acids stored in macrophage ceramide pools, but are also elongated and stored in ceramide pools under conditions of high saturated fatty acid incubations and/or hyperglycemic conditions.