Nitric oxide synthase and postischemic liver injury

Area of Science:

• Physiology
• Immunology
• Hepatology

Background:

• Ischemia and reperfusion (I/R) injury is a significant clinical problem.
• Nitric oxide synthase (NOS) isoforms, endothelial (eNOS) and inducible (iNOS), are implicated in I/R injury.
• The specific roles of eNOS and iNOS in liver I/R injury remain unclear.

Purpose of the Study:

• To investigate the roles of eNOS and iNOS in I/R-induced liver injury in vivo.
• To compare liver injury severity in eNOS-deficient and iNOS-deficient mice.

Main Methods:

• Induction of partial liver ischemia (70%) for 45 minutes followed by 5 hours of reperfusion in wild-type (wt), eNOS-deficient, and iNOS-deficient mice.
• Assessment of liver injury by measuring serum alanine aminotransferase (ALT) levels.
• Histopathological examination and myeloperoxidase (MPO) determination to assess neutrophil infiltration.

Main Results:

• Significant liver injury, indicated by elevated ALT, occurred in wt mice after I/R.
• No significant neutrophil infiltration was observed in the liver at the assessed time point.
• eNOS-deficient mice exhibited significantly enhanced liver injury compared to wt mice.
• iNOS-deficient mice showed no significant difference in liver injury compared to wt mice.

Conclusions:

• Endothelial nitric oxide synthase (eNOS)-derived nitric oxide (NO) plays a protective role in limiting liver I/R injury.
• Inducible nitric oxide synthase (iNOS)-derived NO does not appear to play a significant role in this model of liver I/R injury.
• Targeting eNOS may offer a therapeutic strategy for mitigating liver I/R injury.