Examination of intrahepatic flow distribution by vital staining with rhodamine 6G in isolated perfused rat liver

We previously reported that intrahepatic flow disturbance can be detected b y vital staining of the liver with a fluorescent dye (Masuda et al., Bioche m Pharmacol, 53, 1779-1787 (1997)). To evaluate further use of this method, a detailed study was performed. The isolated perfused rat liver was vitall y stained with rhodamine 6G (R-6G) and perfusion-fixed, and cross and horiz ontal sections were examined by fluorescence microscopy. In the control liv er, R-6G staining was localized to periportal hepatocytes and was distribut ed evenly throughout the liver, indicating a homogeneous perfusion. Finer e xamination of the thick sections and reconstruction of a three-dimensional flow pattern revealed intricate vascular networks together with the sinusoi ds in different portions of the liver. In a flow-redistribution model, i.e. , under hepatic nerve stimulation, the extensive flow redistribution to the deeper portion of the liver was found to occur via short branches sprouted from large portal veins, with minimal perfusion of the liver margin. Thus, visualization of hepatic microvasculature enables anatomical analysis of f low disturbance. The method is indirect but simple and may help detect intr ahepatic flow disturbance that could be evoked by various factors.