PCA score plot of hydrophilic liver extracts from the rats sacrificed immediately after anesthesia. (A) Each plot represents the metabolic data set from an individual rat. Groups are delineated as follows: control (black), propofol (white), dexmedetomidine (blue), sevoflurane (yellow), isoflurane (purple). The plot for each group was clearly divided into separate clusters. In particular, the propofol group was separated from the other groups in the direction of PC1 dominantly. The dexmedetomidine group was separated from the other groups in the direction of PC2. The separation in data clusters was subtler when comparing the inhalational anesthetic groups and the control group. Variables (n = 31 reduced from 186). (B) PC loading plot versus chemical shift are graphically illustrated. The numbers indicate the center value of the integral area of each of the conditions as follows: 1.19 and 1.22 ppm (3-D-hydroxybutyrate (3-D-HB)), 1.32 and 1.35 ppm (lactate), 2.40 ppm (succinate), 2.46 ppm (glutamine), 3.20 ppm (choline), 3.22 ppm (choline, phosphocholine), 3.24 ppm (glycerophosphorylcholine (GPC)), 3.28 ppm (trimethylamine-N-oxide (TMAO)), 3.43 ppm (taurine), 3.75 (mannitol), 3.91 (betaine) and 3.30-4.00 ppm (glucose). (C) Each plot represents the PC loading plot of individual data sets to distinguish single putative NMR peaks responsible for the clustering pattern observed in the PCA score plot. The 3.28 ppm (TMAO) peak was an effective metabolite used to separate the PC scores in the PC1 direction. The 3.24 ppm (GPC) peak was also effective for separation in the PC2 direction.