UCSF

Background/aims

Acute hyperglycemia is known to worsen ischemia/reperfusion (I/R) injury following myocardial infarction and stroke. We investigated whether acute hyperglycemia worsens injury and amplifies the inflammatory response evoked by hepatic I/R.

Methods

Rats were pretreated with an intraperitoneal injection of 25% glucose or 0.9% sodium chloride (10 ml/kg BW). Subsequently, rats underwent partial (70%) hepatic ischemia for 45 min. After 4 h of reperfusion, hepatic injury, oxidative stress, inflammation, and heat shock protein expression were assessed.

Results

Liver injury was increased in the hyperglycemic group with alanine aminotransferase (ALT) and aspartate aminotransferease (AST) serum concentrations of 7,832 +/- 3,374 and 10,677 +/- 4,110 U/L compared to 3,245 +/- 2,009 and 5,386 +/- 3,393 U/L (p < 0.05 vs. control). Hyperglycemic I/R was associated with increased liver nitrotyrosine concentrations and increased neutrophil infiltration. I/R upregulated the protective heat shock proteins HSP32 and HSP70 in control animals, but this protective mechanism was inhibited by hyperglycemia: HSP32 expression decreased from 1.97 +/- 0.89 (control) to 0.46 +/- 0.13 (hyperglycemia), HSP70 expression decreased from 18.99 +/- 11.55 (control) to 3.22 +/- 0.56 (hyperglycemia), (expression normalized to sham, both p < 0.05 vs. control I/R).

Conclusions

Acute hyperglycemia worsens hepatic I/R injury by amplifying oxidative stress and the inflammatory response to I/R. The increase in injury is associated with a downregulation of the protective heat shock proteins HSP32 and HSP70.