Direct visualization of functional heterogeneity in hepatobiliary metabolism using 6-CFDA as model compound

Hepatobiliary metabolism is one of the major functions of the liver. However, little is known of the relationship between the physiological location of the hepatocytes and their metabolic potential. By the combination of time-lapse multiphoton microscopy and first order kinetic constant image analysis, the hepatocellular metabolic rate of the model compound 6-carboxyfluorescein diacetate (6-CFDA) is quantified at the single cell level. We found that the mouse liver can be divided into three zones, each with distinct metabolic rate constants. The sinusoidal uptake coefficients k₁ of Zones 1, 2, and 3 are respectively 0.239 ± 0.077, 0.295 ± 0.087, and 0.338 ± 0.133 min^-1, the apical excreting coefficients k₂ of Zones 1, 2, and 3 are 0.0117 ± 0.0052, 0.0175 ± 0.0052, and 0.0332 ± 0.0195 min^-1, respectively. Our results show not only the existence of heterogeneities in hepatobiliary metabolism, but they also show that Zone 3 is the main area of metabolism.