Quantitative analysis of erythrocyte velocity in rat liver after acute ethanol administration

Hepatic microcirculation is thought to be closely associated with the liver function. The present study was aimed to quantify changes in hepatic microcirculation after acute ethanol administration using a photometric device. Male Wistar rats were anesthetized with pentobarbital sodium (35 mg/kg) intraperitoneally. After laparotomy, a lobe of the liver was exposed and placed on the cover glass at the window of plastic stage, and observed using inverted intravital fluorescence microscopy assisted by a silicon intensified target camera. Erythrocytes were labeled with fluorescein isothiocyanate (FITC) according to the method of Zimmerhackl et al, and injected from the catheter placed at the aortic arch. FITC-labeled red blood cells (FITC-RBCs) recirculated continuously and resembled native cells in their flow properties. Ethanol (20%; 3 g/kg, 30%; 4.5 g/kg, 40%; 6 g/kg) was administered through the stomach tube. The microfluorograph of hepatic microcirculation was then recorded on a videotape. The velocity of FITC-RBCs in sinusoids was measured with a multipurpose computerized image analyzing system by replaying the video images. Portal pressure, mean arterial pressure, and central venous pressure were also monitored. The velocity of FITC-RBCs in the sinusoid increased by 54% at 10-20 min after 20% ethanol administration and remained at higher than the basal level throughout the period of the experiment. The velocity after 30% ethanol administration increased in some experiments and decreased in the others at the end of the experiment (60 min after acute ethanol administration). However, the velocity decreased by 26% at 60 min after 40% ethanol administration. Portal pressure increased by 16% at 45-60 min after 20% ethanol administration, and increased by 23% at 30 min after 40% ethanol administration, while mean arterial pressure and central venous pressure had no significant change. The method in this study is the first approach to visualize hepatic microcirculation by FITC-RBCs and measure erythrocyte velocity in the sinusoid using a multipurpose computerized image analysis system. The current results suggest that high concentration of ethanol may disturb hepatic microcirculation at the sinusoidal level.