Quantification of hepatic microcirculation heterogeneity of perfusion: effects of endothelin-1

Stress alters hepatic perfusion heterogeneously leading to mismatch of oxygen supply and demand. Endothelin-1 (ET-1) has been linked to stress-mediated microcirculation disruption; however, perfusion heterogeneity is difficult to quantify. Therefore, we developed an image analysis based automated methodology for quantification of heterogeneity (Ht) of perfusion from hepatic intravital microscopy images (HIVM). In vivo assessment of the liver microcirculation flow distribution, before and after ET-1 infusion, was performed in male Sprague-Dawley rats using HIVM combined with FITC-labeled RBC infusion. Our method aimed to analyze parallel/spatial and series/temporal intralobular Ht of perfusion as well as interlobular Ht of perfusion and was based on automated RBC detection, tracking, and motion analysis. Compared with manual analysis, this method detected 40 times more RBC without increasing false positives (<0.5%). At baseline, parallel/spatial Ht was higher than series/temporal Ht of perfusion which suggested higher hepatic stellate cells asynchrony between sinusoids than within the same sinusoid. Following ET-1 infusion, parallel/spatial Ht transiently increased contrasting with a decrease in series/temporal Ht. In conclusion, we proposed a HIVM analysis methodology that allows assessment of Ht of perfusion within and between hepatic lobules and improved our understanding of ET-1 mediated effects on the hepatic microcirculation.