Increased portal endothelin-1 level is associated with the liver function after cardiopulmonary bypass in rabbits: influence of hypothermia on the damage.

The purpose of this study was to prove the hypothesis that ET-1 production is increased in the splanchnic-hepato circulation during cardiopulmonary bypass (CPB) with or without hypothermia and this greatly affects hepatocellular function after surgery. Twelve Japanese white rabbits were used. In group I (n = 6), the rectal temperature was kept at 37.0 degrees C during CPB (90 min). In group II (n = 6), the rectal temperature was lowered to 26 degrees C during the first 30 minutes and then increased to 37 degrees C for the following 60 minutes. In group I, surface liver tissue blood flow (LBF) remained stable during CPB. While, in group II, LBF was significantly reduced to 66.9% of baseline values during hypothermic CPB, but it increased during the rewarming phase to 84.3% of the baseline value (p = 0.0070). At the end of CPB, portal ET-1 levels were increased in both groups, but they were significantly higher in group II (7.32 +/- 0.50 pg/ml and 9.29 +/- 0.61 pg/ml, respectively). Serum GOT, GPT, LDH and arterial ammonia levels were also higher in group II. Portal ET-1 levels had a significant positive correlation with those liver enzymes. Histopathological examination after CPB showed severe damage of the hepatic parenchyma in zone 3 associated with microvesicular fatty infiltration in group II.