Nitric oxide inhibits peroxide-mediated endothelial toxicity.
BACKGROUND
Oxidant molecules and nitric oxide (NO) have each been implicated as mediators of endothelial cell damage, but the biologic effect of these molecules acting in concert is incompletely understood.


METHODS
We studied the effects of an NO donor, S-nitroso-acetyl-D,L-penicillamine (SNAP), in combination with the peroxidants tert-butyl hydroperoxide (TBH) and hydrogen peroxide (H2O2) on rabbit aortic endothelial cells in culture. Cell viability was assessed using Alamar blue, a nontoxic dye indicator of cell metabolism. Lipid peroxidation was assessed using a chemiluminescent single-photon counting technique.


RESULTS
After 90 min exposure to test reagents, there was concentration-dependent cytotoxicity for both TBH and H2O2. Peroxidant-induced cytotoxicity was significantly ameliorated by SNAP (10(-4)-10(-3)M). N-Acetylpenicillamine and NO-depleted SNAP failed to demonstrate a cytoprotective effect against peroxidant cellular injury, thus implicating NO as the agent responsible for the protective effect. SNAP reduced lipid peroxidation caused by 10(-3) M TBH in a dose-dependent manner. Preincubation of cells with SNAP before exposure to peroxidants alone had no effect on toxicity.


CONCLUSIONS
NO is cytoprotective to the endothelium in the presence of peroxidants through a reduction of lipid peroxidation.
Degnim
A C
AC
Department of Surgery, University of North Carolina at Chapel Hill 27599, USA.
Morrow
S E
SE
Ku
J
J
Zar
H A
HA
Nakayama
D K
DK
D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000506:poisoning*; D008054:Lipid Peroxides / Q000037:antagonists & inhibitors / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D016877:Oxidants / Q000037:antagonists & inhibitors / Q000506:poisoning*; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D010545:Peroxides / Q000037:antagonists & inhibitors / Q000506:poisoning*; D011817:Rabbits; D026423:S-Nitroso-N-Acetylpenicillamine; D020122:tert-Butylhydroperoxide
D004791:Enzyme Inhibitors; D008054:Lipid Peroxides; D016877:Oxidants; D010545:Peroxides; D009569:Nitric Oxide; C010005:N-acetylpenicillamine; D026423:S-Nitroso-N-Acetylpenicillamine; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D010396:Penicillamine