Endothelially derived nitric oxide affects the severity of early acetaminophen-induced hepatic injury in mice.
OBJECTIVE
The precise mechanism of hepatocellular toxicity following acetaminophen (APAP) poisoning remains unclear. Nitric oxide is implicated in APAP toxicity as an inflammatory signaling molecule and as a precursor to the free radical peroxynitrate. The effects of inducible nitric oxide synthase (iNOS)-derived NO in APAP toxicity are known; however, the role of endothelial nitric oxide synthase (eNOS)-derived NO is unknown. The authors sought to evaluate the effect of eNOS-derived NO during APAP toxicity.


METHODS
C57BL6/J mice deficient in eNOS (eNOS KO) or iNOS (iNOS KO) and wild-type mice (WT) were treated with 300 mg/kg APAP. Alanine aminotransferase levels and plasma nitrate and nitrite levels were measured. Hypoxia inducible factor (HIF)-1alpha and Glucose Transporter 1 (Glut-1) levels were determined by Western blot.


RESULTS
Alanine aminotransferase levels were significantly elevated in all treated animals. Alanine aminotransferase levels were significantly lower in eNOS KO and iNOS KO than in treated WT animals. Plasma nitrate/nitrite levels were significantly higher in WT animals than in iNOS KO and eNOS KO animals. HIF-1alpha expression was increased in WT mice and decreased in iNOS KO mice. Glut-1 is a downstream, indirect marker of HIF function. Glut-1 expression was increased in WT and eNOS KO mice.


CONCLUSIONS
Deficiency of either iNOS or eNOS results in decreased NO production and is associated with reduced hepatocellular injury following APAP poisoning. HIF-1alpha and Glut-1 levels are increased following APAP poisoning, implying that HIF-1alpha is functional during the pathogenic response to APAP poisoning.
Salhanick
Steven D
SD
Department of Emergency Medicine, Beth Israel Deaconess Hospital, Boston, MA, USA.
Orlow
Daniel
D
Holt
Doug E
DE
Pavlides
Stavros
S
Reenstra
Wende
W
Buras
Jon A
JA
D000082:Acetaminophen / Q000506:poisoning*; D000410:Alanine Transaminase / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D056486:Chemical and Drug Induced Liver Injury; D004195:Disease Models, Animal; D016166:Free Radical Scavengers / Q000378:metabolism*; D051272:Glucose Transporter Type 1 / Q000187:drug effects / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000187:drug effects / Q000378:metabolism; D008107:Liver Diseases / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D009566:Nitrates / Q000097:blood; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000172:deficiency; D052250:Nitric Oxide Synthase Type III / Q000172:deficiency; D009573:Nitrites / Q000097:blood; D012016:Reference Values
D016166:Free Radical Scavengers; D051272:Glucose Transporter Type 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D000082:Acetaminophen; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D000410:Alanine Transaminase