Serotonin activity and liver dysfunction following hepatic ischemia and reperfusion.

: Serotonin (5-hydroxytriptamine; 5-HT), which is stored in platelets, is known to induce vasoconstriction and promote platelet aggregation. More recent studies suggest that serotonin also plays a role in organ injury after ischemia and reperfusion. The purpose of this study was to characterize the role of 5-HT and platelet function in the pathogenesis of hepatic ischemia-reperfusion injury. Under the portocaval shunt, 60 or 90 min of complete warm ischemia of canine liver was induced by Pringle's maneuver, followed by reperfusion for 120 min. Time-matched, sham-operated animals served as controls. Hepatic tissue blood flow and various parameters of hepatic vein blood (ALT, LDH, platelet count and platelet aggregation) were measured before and after reperfusion. 5-HT levels in portal vein and hepatic vein were also assayed. Hepatic ischemia and reperfusion resulted in liver hypoperfusion, hepatocellular dysfunction, increased platelet aggregation, increased 5-HT levels, and hepatic microcirculation injury. These results suggest that the endogenous 5-HT released from platelet may contribute to liver tissue hypoperfusion following hepatic ischemia-reperfusion.