Loss of GSH and thiol enzymes in endothelial cells exposed to sublethal concentrations of hypochlorous acid.
We investigated the effect of sublethal concentrations of hypochlorous acid (HOCl) on intracellular thiol groups. Exposure of human umbilical vein endothelial cells to HOCl caused a decrease in cell viability, with concentrations of </=25 microM HOCl being sublethal. At these concentrations, we saw a loss of glutathione and total protein thiol groups. Of the thiol enzymes we investigated, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was particularly susceptible to inactivation, creatine kinase was moderately susceptible, and lactate dehydrogenase was unaffected by HOCl at the concentrations used. Similar results were obtained with HOCl generated over 30 min by myeloperoxidase. GAPDH activity could be regenerated on reincubation of cells in Hanks' balanced salt solution or reduction with dithiothreitol. In contrast, glutathione loss was not reversible, and further decreased with time. Cellular ATP levels decreased with sublethal HOCl concentrations and this appeared to be unrelated to the inactivation of GAPDH. Our results demonstrate that intracellular thiol groups differ in their reactivity with HOCl and suggest that HOCl may be able to regulate specific cellular functions.
Pullar
J M
JM
Free Radical Research Group, Department of Pathology, Christchurch School of Medicine, Christchurch, New Zealand. juliet.pullar@chmeds.ac.nz
Winterbourn
C C
CC
Vissers
M C
MC
D000255:Adenosine Triphosphate / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003402:Creatine Kinase / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism* / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D005978:Glutathione / Q000037:antagonists & inhibitors*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006801:Humans; D006997:Hypochlorous Acid / Q000494:pharmacology* / Q000506:poisoning; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009994:Osmolar Concentration; D013438:Sulfhydryl Compounds / Q000037:antagonists & inhibitors*
D013438:Sulfhydryl Compounds; D006997:Hypochlorous Acid; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D003402:Creatine Kinase; D005978:Glutathione