Antioxidants reduce peroxyl-mediated inhibition of mitochondrial transcription.
We have recently shown that the mitochondrial transcription system is extremely sensitive to inhibition by peroxyl radicals generated by either 2,2'-azobis(2-amidinopropane) (AAPH) or 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN), and that this inhibition occurs prior to detectable evidence of lipid peroxidation as measured by thiobarbituric acid (TBA)-reactive substances, 4-hydroxynonenal accumulation, and oxygen consumption. In this report, we further confirm that mitochondrial transcription is sensitive to oxidative stress. We also demonstrate that alpha-tocopherol, ascorbate, and glutathione can partially attenuate these effects, but none of the three, nor the three together, are capable of completely preventing this oxidant-induced repression. This suggests that these physiological antioxidants, while capable of preventing lipid peroxidation chain reactions, are less effective at protecting the mitochondrial transcriptional machinery against this oxidative insult.
Kristal
B S
BS
Department of Physiology, University of Texas Health Science Center, San Antonio 78284-7756.
Park
B J
BJ
Yu
B P
BP
D000578:Amidines / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology; D001391:Azo Compounds / Q000378:metabolism; D005978:Glutathione / Q000494:pharmacology; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D009570:Nitriles / Q000378:metabolism; D010545:Peroxides / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D014158:Transcription, Genetic / Q000187:drug effects*; D014810:Vitamin E / Q000494:pharmacology
D000578:Amidines; D000975:Antioxidants; D001391:Azo Compounds; D009570:Nitriles; D010545:Peroxides; C055792:2,2'-azobis(2,4-dimethylvaleronitrile); D014810:Vitamin E; C049375:perhydroxyl radical; C046728:2,2'-azobis(2-amidinopropane); D005978:Glutathione; D001205:Ascorbic Acid