Niknahad H, Khan S, O'Brien PJ. Oxygen dependence of hepatocyte susceptibility to mitochondrial respiratory inhibitors.
Biochem Pharmacol 1995;
50:1859-65. [PMID:
8615865 DOI:
10.1016/0006-2952(95)02079-9]
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Abstract
Most zone 3 specific hepatotoxins or their metabolites are mitochondrial toxins, and yet the susceptibility of hepatocytes to respiratory inhibitors at the low O2 concentrations found in zone 3 is not known. Potassium cyanide (CN) and antimycin A (AA) were found to be 5- and 2-fold more cytotoxic at 1% than at 95% O2, respectively. CN also inhibited the respiration of hepatocytes 36% more at 1% O2 than at 95% O2; however, AA inhibited the respiration to the same level at 1% and 95% O2. CN but not AA depleted ATP levels of hepatocytes more extensively at 1% than at 95% O2. The CN-trapping agents dihydroxyacetone, glyceraldehyde, alpha-ketoglutarate and pyruvate prevented CN-induced cytotoxicity more effectively at 95% O2 than at 1% O2. In contrast, thiosulfate was less effective in preventing CN toxicity at 95% than at 1% O2. Hepatocyte thiocyanate formation from CN and thiosulfate was much faster at 1% than at 95% O2, suggesting that rhodanese, the mitochondrial enzyme that forms thiocyanate from CN and thiosulfate, is more effective at 1% O2 than at 95% O2.
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