Nitric oxide inhibits stress-induced endothelial cell apoptosis.
OBJECTIVE
To determine a mechanism by which nitric oxide alters induction of stress-induced endothelial cell apoptosis in vitro. Apoptosis is a form of cellular suicide that has been implicated in the pathogenesis of multiple organ dysfunction syndrome.


METHODS
Prospective, controlled trial.


METHODS
Research laboratory of a large, academic medical center.


METHODS
Cultured primary porcine aortic endothelial cells.


METHODS
Cells were treated with a range of doses of agents that either spontaneously generate nitric oxide (S-nitroso-N-acetyl-D,L-penicillamine [SNAP] or (Z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1- ium-1,2-diolate [DETA-NO]) or block nitric oxide production (Nomega-methyl-L-arginine [L-NMA]). The ability of these agents to alter the rate of cell death by apoptosis (induced by the sequence stimuli lipopolysaccharide [LPS] followed by sodium arsenite) was measured. Mechanistic studies included examining the ability of: a) nitric oxide "donors" to alter nuclear factor kappa B (NF-kappaB) DNA binding activity and the level of IkappaBalpha accumulation; and b) a stable cyclic guanosine monophosphate (cGMP) analog (8-bromo-cGMP) to mimic the effect of nitric oxide donors.


RESULTS
The sequence LPS/sodium arsenite increased the rate of endothelial cell apoptosis (47.4%, p< .05 vs. control), as measured by fluorescent-activated cell scanning using annexin V/propidium iodide staining. DETA-NO generated nitric oxide (as indicated by an increase in the concentration of the stable end-products of nitric oxide metabolism) and decreased the rate of endothelial cell apoptosis (20.6% at a dose of 2 mM, p=.0001 vs. control). DETA-NO also decreased NF-kappaB DNA binding activity and the apparent accumulation of its endogenous inhibitor, IkappaBalpha. The 8-bromo-cGMP did not mimic the effects of nitric oxide donors (DETA-NO) on apoptosis.


CONCLUSIONS
These data suggest that exogenous nitric oxide can block stress-induced endothelial cell apoptosis in vitro. The mechanistic studies are consistent with our hypothesis that inhibitors of NF-kappaB DNA binding activity are associated with protection against apoptosis-inducing stimuli. The results do not support a role for cGMP in mediating the protective effect of DETA-NO in our model.
DeMeester
S L
SL
Department of Surgery, Washington University, St. Louis, MO 63110, USA.
Qiu
Y
Y
Buchman
T G
TG
Hotchkiss
R S
RS
Dunnigan
K
K
Karl
I E
IE
Cobb
J P
JP
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D018053:Arsenites / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000201:enzymology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D008070:Lipopolysaccharides; D009102:Multiple Organ Failure / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011446:Prospective Studies; D017670:Sodium Compounds / Q000494:pharmacology; D013552:Swine; D014226:Triazenes / Q000494:pharmacology*; D019323:omega-N-Methylarginine / Q000494:pharmacology*
C105351:1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene; D018053:Arsenites; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D016328:NF-kappa B; C110881:S-nitro-N-acetylpenicillamine; D017670:Sodium Compounds; D014226:Triazenes; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; C017947:sodium arsenite; D010396:Penicillamine