PURPOSE: Various vasopressor agents are used to raise systemic vascular resistance (SVR) during liver transplantation. After grafted liver was reperfused, postreperfusion syndrome could be treated with various vasopressors. However, epinephrine can decrease the splanchnic perfusion and oxygen saturation and then hepatic blood flow would be jeopardized. Decreased hepatic blood flow might result in centrilobular necrosis which contributes to disruption of liver functions. We tried to know the effect of epinephrine on tissue perfusion of the liver. METHODS: In this study, measurement of hepatic microcirculation (HMC) and hemodynamic changes was performed in eight dogs to investigate the effect of vasopressors on hepatic microcirculation. Animals were divided into four groups in which low-dose epinephrine (0.05mug/Kg/min) and high-dose epinephrine (0.5mug/Kg/min) were randomly infused into the systemic vein and portal vein (1/6 of systemic dose) for ten minutes. Hepatic microcirculation was measured by Thermal Diffusion Probe. RESULTS: At low-dose systemic infusion of epinephrine, mean arterial bloodpressure (MABP), cardiac output (CO), and hepatic microcirculation (HMC) were significantly increased but systemic vascular resistance (SVR) was decreased. On high-dose epinephrine, MABP, CO (P=0.01), and SVR were significantly increased without changes of HMC. Intraportal infusion of low- and high-dose epinephrine increased hepatic vein pressure and SVR, respectively. CONCLUSION: These results would provide clues that systemic low-dose epinephrine infusion is enough to raise HMC and high-dose infusion of epinephrine to raise SVR could be used without jeopardizing HMC.