title: Mass spectrometric imaging of metabolites in kidney tissues from rats treated with furosemide.
abstract: In the kidney, metabolic processes are different among the cortex (COR), outer medulla (OM), and inner medulla (IM). Using matrix-assisted laser desorption/ionization (MALDI) and imaging mass spectrometry (IMS), we examined the change of metabolites in the COR, OM, and IM of the rat kidney after furosemide treatment compared with vehicle-treated controls. Osmotic minipumps were implanted in male Sprague-Dawley rats to deliver 12 mg·day(-1)·rat(-1) of furosemide. Vehicle-treated (n = 14) and furosemide-treated (furosemide rats, n = 15) rats in metabolic cages received a fixed amount of rat chow (15 g·220 g body wt(-1)·day(-1) for each rat) with free access to water intake for 6 days. At day 6, higher urine output (32 ± 4 vs. 9 ± 1 ml/day) and lower urine osmolality (546 ± 44 vs. 1,677 ± 104 mosmol/kgH2O) were observed in furosemide rats. Extracts of COR, OM, and IM were analyzed by ultraperformance liquid chromatography coupled with quadrupole time-of-flight (TOF) mass spectrometry, where multivariate analysis revealed significant differences between the two groups. Several metabolites, including acetylcarnitine, betaine, carnitine, choline, and glycerophosphorylcholine (GPC), were significantly changed. The changes of metabolites were further identified by MALDI-TOF/TOF and IMS. Their spatial distribution and relative quantitation in the kidneys were analyzed by IMS. Carnitine compounds were increased in COR and IM, whereas carnitine and acetylcarnitine were decreased in OM. Choline compounds were increased in COR and OM but decreased in IM from furosemide rats. Betaine and GPC were decreased in OM and IM. Taken together, MALDI-TOF/TOF and IMS successfully provide the spatial distribution and relative quantitation of metabolites in the kidney.
authors.affiliation: Integrated Metabolomics Research Group, Western Seoul Center, Korea Basic Science Institute, Seoul, Korea;
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Jung
authors.affiliation: Department of Biochemistry and Cell Biology, Korea; and BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, School of Medicine, Kyungpook National University, Taegu, Korea.
authors.forename: Mi Suk
authors.initials: MS
authors.lastname: Lee
authors.affiliation: Department of Biochemistry and Cell Biology, Korea; and.
authors.forename: Hyo-Jung
authors.initials: HJ
authors.lastname: Choi
authors.affiliation: Integrated Metabolomics Research Group, Western Seoul Center, Korea Basic Science Institute, Seoul, Korea;
authors.forename: Sunhee
authors.initials: S
authors.lastname: Jung
authors.affiliation: Department of Biochemistry and Cell Biology, Korea; and BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, School of Medicine, Kyungpook National University, Taegu, Korea.
authors.forename: Yu-Jung
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Integrated Metabolomics Research Group, Western Seoul Center, Korea Basic Science Institute, Seoul, Korea;
authors.forename: Geum-Sook
authors.initials: GS
authors.lastname: Hwang
authors.affiliation: Department of Biochemistry and Cell Biology, Korea; and BK21 Plus KNU Biomedical Convergence Program, Department of Biomedical Science, School of Medicine, Kyungpook National University, Taegu, Korea thkwon@knu.ac.kr.
authors.forename: Tae-Hwan
authors.initials: TH
authors.lastname: Kwon
mesh_terms: D000818:Animals; D004232:Diuretics / Q000494:pharmacology*; D004326:Drinking / Q000187:drug effects; D005665:Furosemide / Q000494:pharmacology*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014554:Urination / Q000187:drug effects
chemical_list: D004232:Diuretics; D005665:Furosemide
keywords: carnitine; loop diuretics; metabolomics; urine concentration