2.3. Butyric acid measurements

Mice were subjected to sham or scald injury as described above. On PBD 1–8, stool samples were collected from the cecum and butyric acid levels were analyzed as previously described [35]. Briefly, stool samples were weighed and diluted at a ratio of 1:5 in 25% meta-phosphoric acid. The samples were centrifuged at 16,000g for 15 min at 4.0°C, filtered through 0.45 μm syringe tip filter (Thermo Fischer Scientific, Waltham, MA), and then stored at −80.0°C until ready for analysis. Butyrate concentrations were performed by high performance liquid chromatography (HPLC) using a Rezex ROA-organic acid H+ (8%) 300 × 7.8 mm analytical column (Phenomenex, Torrance, CA) at 65.0°C. A 0.01 N sulfuric acid mobile phase at a flow rate of 0.7 mL/min was used. A UV detector set at wavelength 210 nm monitored the effluent. Butyric acid levels were compared to standards ranging from 1 to 100 mM. Concentrations were corrected for dilution and fecal weight and expressed as μmol per gram of wet weight feces [35, 36].