Increased nitric oxide production in the liver in the perioperative period of partial hepatectomy with Pringleʹs maneuver

Background/Aims: There is no evidence that nitric oxide is produced in the liver during ischemia/reperfusion injury. This study examined the production of nitric oxide and inducible nitric oxide synthase in patients undergoing partial hepatectomy. Methods: Twenty patients undergoing partial hepatectomy with only Pringleʹs maneuver were included. Peripheral blood was taken 1 day before the operation, during the operation (just after laparotomy and the first and last Pringleʹs maneuver) and 1 and 3 days after the operation, for measurement of plasma nitrate/nitrite, endotoxin and cytokine levels. Blood was also sampled from hepatic veins after Pringleʹs maneuver. Two liver specimens were taken from each patient, one before ischemia and one after partial hepatectomy, for the detection of inducible nitric oxide synthase. Results: Average nitrate reached a maximum (33.5±3.4 μmol/l) after the final clamp (hepatic venous level). The increase in nitrate level during the operation correlated with the total duration of clamping. Endotoxin and interleukin-6 levels increased in a similar manner to nitrate levels, but tumor necrosis factor-alpha and interleukin-1 beta levels did not. In liver specimens taken after partial hepatectomy from patients, inducible nitric oxide synthase mRNA and protein were detected. Conclusions: Nitric oxide was producted in livers during ischemia/reperfusion injury and inducible nitric oxide synthase was involved in nitric oxide production.