Acute Hyperglycemia Worsens Hepatic Ischemia/Reperfusion Injury in Rats

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.