Periportal and perivenous hepatocytes retain their zonal characteristics in primary culture.
ABSTRACT Periportal and perivenous hepatocytes from rat liver were isolated by combined digitonin-collagenase perfusion, and gluconeogenesis, urea synthesis and fatty acid synthesis was measured both in freshly isolated cells and in primary culture. A periportal zonation of gluconeogenesis and urea synthesis of about 3 and 1.5 fold, respectively, was observed. This zonation persisted unchanged for 23 hours in culture under identical conditions of incubation for periportal and perivenous cells. Fatty acid synthesis was not zonated.
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ABSTRACT: Despite a longstanding research interest ever since the early work by Claude Bernard, the functional significance of autonomic liver innervation, either sympathetic or parasympathetic, is still ill defined. This scarcity of information not only holds for the brain control of hepatic metabolism, but also for the metabolic sensing function of the liver and the way in which this metabolic information from the liver affects the brain. Clinical information from the bedside suggests that successful human liver transplantation (implying a complete autonomic liver denervation) causes no life threatening metabolic derangements, at least in the absence of severe metabolic challenges such as hypoglycemia. However, from the benchside, data are accumulating that interference with the neuronal brain-liver connection does cause pronounced changes in liver metabolism. This review provides an extensive overview on how metabolic information is sensed by the liver, and how this information is processed via neuronal pathways to the brain. With this information the brain controls liver metabolism and that of other organs and tissues. We will pay special attention to the hypothalamic pathways involved in these liver-brain-liver circuits. At this stage, we still do not know the final destination and processing of the metabolic information that is transferred from the liver to the brain. On the other hand, in recent years, there has been a considerable increase in the understanding which brain areas are involved in the control of liver metabolism via its autonomic innervation. However, in view of the ever rising prevalence of type 2 diabetes, this potentially highly relevant knowledge is still by far too limited. Thus the autonomic innervation of the liver and its role in the control of metabolism needs our continued and devoted attention.Biochimica et Biophysica Acta 04/2010; 1802(4):416-31. · 4.66 Impact Factor
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ABSTRACT: Periportal and perivenous hepatocytes were isolated from rat liver by digitonin/collagenase perfusion for investigating the acinar distribution of taurocholate uptake. Statistical analysis revealed that uptake of taurocholate by periportal, perivenous and regular (whole acinus) hepatocytes in Na+-containing and -free buffer was best described by one saturable component. Total taurocholate uptake measured in Na+-containing buffer was significantly higher in perivenous (Vmax=7.5 nmol/(min mg protein)) than in periportal hepatocytes (Vmax=5.4 nmol/(min mg protein)). Uptake by regular hepatocytes was well between the values of periportal and perivenous hepatocytes (Vmax=6.7 nmol/(min mg protein)). The Km-values were not different among the zonal regions. In Na+-free buffer, Km and Vmax of taurocholate uptake calculated for all fractions were similar. During cultivation of hepatocytes as monolayer total taurocholate uptake strongly decreased and the zonal differences observed in freshly isolated cells in suspension disappeared. Initial uptake rates of Na+-independent taurocholate uptake and the ATP-content of the hepatocytes were constant. Our results indicate an acinar gradient of Na+-dependent taurocholate uptake activity, which may improve the clearance of bile salts from portal blood and protect periportal hepatocytes against a too high intracellular bile salt concentration.Hepatology Research 02/2004; 28(2):114–123. · 2.07 Impact Factor
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ABSTRACT: Signaling through the Wnt/β-catenin pathway is a crucial determinant of hepatic zonal gene expression, liver development, regeneration, and tumorigenesis. Transgenic mice with hepatocyte-specific knockout of Ctnnb1 (encoding β-catenin) have proven their usefulness in elucidating these processes. We now found that a small number of hepatocytes escape the Cre-mediated gene knockout in that mouse model. The remaining β-catenin-positive hepatocytes showed approximately 25% higher cell volumes compared to the β-catenin-negative cells and exhibited a marker protein expression profile similar to that of normal perivenous hepatocytes or hepatoma cells with mutationally activated β-catenin. Surprisingly, the expression pattern was observed independent of the cell's position within the liver lobule, suggesting a malfunction of physiological periportal repression of perivenously expressed genes in β-catenin-deficient liver. Clusters of β-catenin-expressing hepatocytes lacked expression of the gap junction proteins Connexin 26 and 32. Nonetheless, β-catenin-positive hepatocytes had no striking proliferative advantage, but started to grow out on treatment with phenobarbital, a tumor-promoting agent known to facilitate the formation of mouse liver adenoma with activating mutations of Ctnnb1. Progressive re-population of Ctnnb1 knockout livers with wild-type hepatocytes was seen in aged mice with a pre-cirrhotic phenotype. In these large clusters of β-catenin-expressing hepatocytes, perivenous-specific gene expression was re-established. In summary, our data demonstrate that the zone-specificity of a hepatocyte's gene expression profile is dependent on the presence of β-catenin, and that β-catenin provides a proliferative advantage to hepatocytes when promoted with phenobarbital, or in a pre-cirrhotic environment.Histochemie 10/2010; 134(5):469-81. · 2.61 Impact Factor