High-Speed Microdialysis-Capillary Electrophoresis Assays for Measuring Branched Chain Amino Acid Uptake in 3T3-L1 cells

摘要

We have developed a high-throughput micro dialysis-capillary electrophoresis (MD-CE) assay-for monitoring branched chain amino acid, (BCAA) uptake/release dynamics in 3T3-L1 cells. BCAAs (i.e., isoleucine, leucine, and,valitie) and their downstream metabolites (i.e., alanine, glutamine, "and glutamate) are important indicators of adipocyte lipogenesis. To perform an analysis, amino acids were sampled using microdialysis, fluorescently labeled in. an online reaction, separated using CE, and detected using laser induced fluorescence-(LIF) in a sheath flow cuvette. Separation conditions were optimized for the resolution of the BCAAs isoleucine, leucine, and valine, as well as 13 other amino acids, including ornithine, alanine, glutamine, and glutamate. CE separations were performed in <30 s, and the temporal resolution of the online MD-CE assay was <60 s. Limits of detection (LOD) were 400,100, and 100 nM for isoleucine, leucine, and valine, reSpectively. MD-CE dramatically improved throughput in comparison 'to traditional offline CE methods, allowing 8 replicates of 15-samples (i.e., 120 analyses) to be assayed in <120 min. The MD-CE assay was used to assess the metabolism dynamics of 3T3-Li cells over time, confirming the utility of the assay.