title: Direct evidence of nitric oxide presence within mitochondria.
abstract: Nitric oxide (NO) has been implicated in the modulation of mitochondrial respiration, membrane potential, and subsequently in apoptosis. Although the presence of a mitochondrial NO synthase (mtNOS) has been described, there is no direct evidence in vivo of the presence of NO within mitochondria. It was the aim of this study to demonstrate the in vivo production of NO within mitochondria. Using the novel fluorometric NO detection system, 4,5-diaminofluorescein diacetate (DAF-2/DA), we observed the presence of NO production in PC12 and COS-1 cells by conventional and confocal fluorescence microscopy. Part of the overall NO signal was colocalized within a subpopulation of mitochondria, labeled with the potential-dependent probe MitoTracker red. These findings demonstrate for the first time that the subcellular distribution of NO production is consistent with the presence of a mitochondrial NOS. Our results provide a new tool to directly study the modulatory role of NO in mitochondrial respiration and membrane potential, in vivo.
authors.affiliation: Mental Health Research Institute, University of Michigan, Ann Arbor 48109-0720, USA. molf@umich.edu
authors.forename: M O
authors.initials: MO
authors.lastname: López-Figueroa
authors.forename: C
authors.initials: C
authors.lastname: Caamaño
authors.forename: M I
authors.initials: MI
authors.lastname: Morano
authors.forename: L C
authors.initials: LC
authors.lastname: Rønn
authors.forename: H
authors.initials: H
authors.lastname: Akil
authors.forename: S J
authors.initials: SJ
authors.lastname: Watson
mesh_terms: D000818:Animals; D019556:COS Cells; D019069:Cell Respiration; D019793:Fluorescein; D005456:Fluorescent Dyes; D008564:Membrane Potentials; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D009930:Organic Chemicals; D016716:PC12 Cells; D051381:Rats
chemical_list: C111205:4,5-diaminofluorescein; D005456:Fluorescent Dyes; D009930:Organic Chemicals; C107472:red dye CMXRos; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019793:Fluorescein