title: Do mitochondria make nitric oxide? no?
abstract: Several papers have claimed that mitochondria contain nitric oxide synthase (NOS) and make nitric oxide (NO*) in amounts sufficient to affect mitochondrial respiration. However, we found that the addition of L-arginine or the NOS inhibitor L-NMMA to intact rat liver mitochondria did not have any effect on the respiratory rate in both State 3 and State 4. We did not detect mitochondrial NO* production by the oxymyoglobin oxidation assay, or electrochemically using an NO* electrode. An apparent NO* production detected by the Griess assay was identified as an artifact. NO* generated by eNOS added to the mitochondria could easily be detected, although succinate-supplemented mitochondria appeared to consume NO*. Our data show that NO* production by normal rat liver mitochondria cannot be detected in our laboratory, even though the levels of production claimed in the literature should easily have been measured by the techniques used. The implications for the putative mitochondrial NOS are discussed.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, National University of Singapore, MD 7 #02-07, 8 Medical Drive, Singapore 117597, Singapore.
authors.forename: Yvonne Mei Sian
authors.initials: YM
authors.lastname: Tay
authors.forename: Kok Seong
authors.initials: KS
authors.lastname: Lim
authors.forename: Fwu-Shan
authors.initials: FS
authors.lastname: Sheu
authors.forename: Andrew
authors.initials: A
authors.lastname: Jenner
authors.forename: Matthew
authors.initials: M
authors.lastname: Whiteman
authors.forename: Kim Ping
authors.initials: KP
authors.lastname: Wong
authors.forename: Barry
authors.initials: B
authors.lastname: Halliwell
mesh_terms: D000818:Animals; D004566:Electrodes; D005609:Free Radicals / Q000378:metabolism*; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019802:Succinic Acid / Q000378:metabolism; D013997:Time Factors
chemical_list: D005609:Free Radicals; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D019802:Succinic Acid; D019001:Nitric Oxide Synthase; D010100:Oxygen