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: 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: Liver fatty acid binding protein may play a role in the intracellular transport and compartmentation of long-chain fatty acid metabolism. The distribution of liver fatty acid binding protein in the hepatic acinus was determined by means of immunocytochemistry as well as by measurement of liver fatty acid binding protein in cellular protein selectively released from zone 1 and zone 3 cells by means of anterograde and retrograde liver perfusion with digitonin. In untreated male rats, specific immunocytochemical staining for liver fatty acid binding protein showed a declining portal-to-central hepatocellular gradient in intensity, consistent with the portal-to-central ratio of liver fatty acid binding protein abundance measured in effluents from digitonin-perfused livers of 1.6:1. Female and clofibratetreated male rats, in both of which hepatic synthesis and abundance of liver fatty acid binding protein are greater than in untreated males, differed as well in the pattern of acinar expression of this protein. In females, periportal concentrations of liver fatty acid binding protein determined from the effluent of livers perfused anterograde with digitonin were similar to male values, whereas liver fatty acid binding protein concentration in pericentral hepatocytes determined from the effluent of retrograde perfused livers was increased, resulting in a marked attenuation of the portal-to-central gradient of this protein; this was also apparent on immunocytochemistry. Clofibrate-treated rats, in contrast, displayed a panacinar increase in liver fatty acid binding protein with maintenance of the portal-to-central ratio observed in untreated males. We conclude that there exists a declining portal-to-central gradient in liver fatty acid binding protein cellular abundance in the hepatic acinus of untreated male rats. Furthermore, the increased synthesis and abundance of liver fatty acid binding protein in female and clofibrate-treated male rats results in two different alterations in the acinar expression of this protein, i.e. a pericentral increase (female) or a panlobular increase (clofibrate). Elucidation of the relationship between the zonation of hepatic fatty acid metabolism and the acinar expression of liver fatty acid binding protein should provide a more detailed understanding of the function of this protein.Hepatology 12/1988; 9(1):12 - 21. · 12.00 Impact Factor
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ABSTRACT: A hypothesis for the hormonal regulation of gluconeogenesis, in which increases in cytosolic free-Ca2+ levels ([Ca2+]i) play a major role, is presented. This hypothesis is based on the observation that gluconeogenic hormones evoke a common pattern of Ca2+ redistribution, resulting in increases in [Ca2+]i. Current concepts of hormonally evoked Ca2+ fluxes are presented and discussed. It is suggested that the increase in [Ca2+]i is functionally linked to stimulation of gluconeogenesis. The stimulation of gluconeogenesis is accomplished in two ways: (1) by increasing the activities of the Krebs cycle and the electron-transfer chain, thereby supplying adenosine triphosphate (ATP) and reducing equivalents to the process; and (2) by stimulating the activities of key gluconeogenic enzymes, such as pyruvate carboxylase. The hypothesis presents a conceptual framework that ties together two interrelated manifestations of hormone action: signal transduction and metabolism.Metabolism: clinical and experimental 01/1996; 45(3):389-403. · 3.10 Impact Factor