Quantitative Analysis of Sphingomyelin by High-Performance Liquid Chromatography after Enzymatic Hydrolysis

Sphingomyelin is the most abundant sphingolipid in mammalian cells and is mostly present in the plasma membrane. A new analytical method using high-performance liquid chromatography (HPLC) was developed to quantify sphingomyelin in mouse plasma and tissues, 3T3-L1 cells, rat aortic smooth muscle cells, and HT-29 cells. Sphingomyelin and dihydrosphingomyelin, an internal standard, were separated by high-performance thin-layer chromatography and simultaneously hydrolyzed with sphingolipid ceramide N-deacylase and sphingomyelinase to release sphingosine and dihydrosphingosine, respectively. Sphingomyelin content was measured by HPLC following o-phthalaldehyde derivatization. Sphingomyelin concentrations in 3T3-L1 cells, rat aortic smoothmuscle cells, and HT-29 cells were 60.10 +/- 0.24, 62.69 +/- 0.08, and 58.38 +/- 0.37 pmol/mu g protein, respectively, whereas those in brain, kidney, and liver of ICR mice were 55.60 +/- 0.43, 43.75 +/- 0.21, and 22.26 +/- 0.14 pmol/mu g protein. The sphingomyelin concentration in mouse plasma was 407.40 +/- 0.31 mu M. The limits of detection and quantification for sphingomyelin were 5 and 20 pmol, respectively, in the HPLC analysis with fluorescence detection. This sensitivity was sufficient for analyzing sphingomyelin in biological samples. In conclusion, this analytical method is a sensitive and specific technique for quantifying sphingomyelin and was successfully applied to diverse biological samples with excellent reproducibility.