Decreased hepatic nitric oxide synthesis during liver surgery

BACKGROUND/AIMS: Liver cells can produce nitric oxide from L-arginine throu gh the action of nitric oxide synthase, but local changes in the concentrat ions of nitric oxide-related metabolites during liver surgery are not well characterized. We investigated such changes during and after liver surgery. METHODOLOGY: We determined nitrite plus nitrate, L-arginine and L-citrullin e concentrations in radial arterial and hepatic venous blood during and aft er liver surgery in 17 patients. Portal venous blood concentrations were al so measured at the end of surgery in 7 patients. RESULTS: Both arterial and hepatic venous nitrite plus nitrate concentratio ns were significantly decreased during surgery and remained low compared to pre-operative values until post-operative day 2. Arterial and hepatic veno us nitrite plus nitrate concentrations were not significantly different. L- arginine concentrations in both arterial and hepatic venous blood were sign ificantly decreased during surgery, but returned to pre-operative levels on post-operative day 1. L-arginine concentrations in hepatic venous blood we re significantly lower than in arterial blood. L-citrulline concentrations in both arterial and hepatic venous blood were significantly decreased duri ng surgery compared to preoperative values, and tend to be decreased until post-operative day 2. L-citrulline concentrations were significantly higher in hepatic venous blood than in arterial blood. CONCLUSIONS: Hepatic nitric oxide production was decreased peri-operatively during liver surgery. The decreases in L-arginine concentrations and in ni tric oxide synthase activity may account for the decrease in nitric oxide p roduction.