Aims

To investigate the effect of moderate hypothermia during CPB on intrahepatic gene expression of TNFα, IL10, apoptosis regulatory proteins (Fas, Bak and Bcl-xL) and hepatic cell death during and after cardiac surgery.

Methods

Pigs were assigned to a temperature (T°) group during standardized cardiopulmonary bypass (CPB): normothermia (T°, 37°C; n = 8) and moderate hypothermia (T°, 28°C; n = 8). Liver probes were taken before and 6 hours after CPB for standard-and immunohistological examinations. Apoptotic cells were detected by TUNEL-staining. Intrahepatic gene expression of TNFα, IL10 and of apoptosis regulating proteins were examined by competitive RT-PCR.

Results

Gene expression of cytokine and apoptosis regulating proteins was not detected before but 6 hours after CPB. Pigs operated on under 28°C showed lower TNFα-mRNA and higher IL10-mRNA than those operated on under 37°C (P < 0.05). While expression of apoptosis regulatory proteins and percentage of apoptotic hepatocytes were similar in both groups, percentage of necrotic hepatocytes was lower in 28°C than in 37°C group (P < 0.05). TNFα-mRNA after CPB was correlated with the percentage of necrotic hepatocytes (P < 0.05).

Conclusions

Moderate hypothermia during CPB provides hepatic protection by increasing IL10- and decreasing intrahepatic TNFα-gene expression without affecting gene expression of apptosis regulatory proteins.