Corresponding stable isotope labeled peptides

Norbuprenorphine (NBUP) and norbuprenorphine-3-β-D-glucuronide (NBUP-G) used in animal studies were provided by the National Institute on Drug Abuse (Bethesda, MD). NBUP, norbuprenorphine-d3 (NBUP- d3) and NBUP-G used for analytical calibrations in LC-MS/MS analysis were from Cerilliant (Round Rock, TX). Optima grade or high-performance liquid chromatography grade methanol, acetonitrile, polyethylene glycol 400, ethanol, formic acid, DMSO, dimethyl sulfoxide and water were from Thermo Fisher Scientific (Waltham, MA) or Acros Organics (Pittsburgh, PA). Isoflurane was purchased from Piramal Healthcare (Mumbai, India) through the University of Washington Medical Center Pharmacy. Synthetic signature peptides for absolute protein quantification by LC-MS/MS were obtained from New England Peptides (Boston, MA). The corresponding stable-isotope-labeled (SIL) peptides were purchased from Thermo Fisher Scientific (Rockford, IL). The protein extraction kit for ProteoExtract native membrane was from Calbiochem (Temecula, CA). Ammonium bicarbonate and sodium deoxycholate were obtained from Thermo Fisher Scientific and MP Biomedicals (Santa Ana, CA), respectively. BCA protein assay and in-solution trypsin digestion kits, iodoacetamide and dithiothreitol were obtained from Pierce Biotechnology (Rockford, IL).