Non-invasive, three-dimensional analysis of hepatic lobular microcirculation.

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Hepatic microcirculation is fundamental system for supplying the oxygen and nutrients to the hepatocytes and sinusoidal cells and for removal of waste matters. For clarifying the role of hepatic microcirculation in patho-genesis and developement of liver diseases, three-dimensional structure of vessels and cells and their functions were studied by in vivo microscope equipped with a sensitive camera and computerized image processing system. Dynamic responses to various exogenous, vasoactive and toxic substances were also investigated by a series of techniques. The findings were as follows:1) In periportal area, the sinusoids were tortuous and formed 3-dimensional networks, the red blood cell flow velocity was slower than in the pericentral area. The sinusoids around the pericentral region were wider, ran parallelly and converged to venules. The velocity around pericentral area was much faster than in periportal area and was positively correlated with the diameter of the vessels. Thus, periportal sinusoids were microcirculatory characteristic of the capillary, while pericentral sinusoids were of the venules.2) The three dimensional structures of the terminal portal and terminal hepatic venules have shown that the distance between the terminal portal venule and the liver surface was larger than that between the terminal hepatic venule and liver surface.3) In vivo epifluorescent microscope system was constructed using SIT camera and videoprocessing system. Transport of fluorescein from periportal to pericentral sinusoids and hepatocytes and from hepatocytes to bile canaliculi were analyzed. A homogeneous uptake by normal hepatocytes and polygonal appearance of bile canalicular network were observed, while in CCl4-treated rats, a marked heterogeneous uptake and secretion were observed, depending on cell damage and microcirculatory disorder.