a) Data for metabolic intermediates in the normal lung are shown in green boxes and data for PAH are represented in pink boxes. PAH patients exhibited higher levels of citrate, cis-aconitate, succinate, and succinyl carnitine. b) The pathway for the tricarboxylic acid (TCA) cycle, the metabolic pathway for glucose oxidation in the mitochondria, is shown. Upregulated metabolic intermediates (citrate, cis-aconitase, succinyl-CoA, and succinate) are shown in red. c) Analysis of gene expression for key enzymes of the TCA cycle. Data from normal lung are represented in blue and data from PAH lung are shown in green. Aco1 (p = 1.068×10-3) andIREB-2were upregulated in the PAH lung sample (p = 1.59e-07), as well as IDH1 for converting isocitrate to α-ketoglutarate with the interconversion of NADP+ to NADPH (p = 4.96×10-9). SUCLA-2, which is one of two genes that encode succinate-CoA ligase for the conversion of succinyl-CoA to succinate with an interconversion of GDP to GTP, was upregulated in PAH patients compared to the normal control (p = 4.17×10-8).