Do mitochondria make nitric oxide? no?
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.
Tay
Yvonne Mei Sian
YM
Department of Biochemistry, Faculty of Medicine, National University of Singapore, MD 7 #02-07, 8 Medical Drive, Singapore 117597, Singapore.
Lim
Kok Seong
KS
Sheu
Fwu-Shan
FS
Jenner
Andrew
A
Whiteman
Matthew
M
Wong
Kim Ping
KP
Halliwell
Barry
B
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
D005609:Free Radicals; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D019802:Succinic Acid; D019001:Nitric Oxide Synthase; D010100:Oxygen