Periportal and perivenous hepatocytes possess different amounts and activities of the rate-generating enzymes of carbohydrate and oxidative energy metabolism and thus different metabolic capacities. This is the basis of the model of metabolic zonation, according to which periportal cells catalyze predominantly the oxidative catabolism of fatty and amino acids as well as glucose release and glycogen formation via gluconeogenesis, and perivenous cells carry out preferentially glucose uptake for glycogen synthesis and glycolysis coupled to liponeogenesis. The input of humoral and nervous signals into the periportal and perivenous zones is different; gradients of oxygen, substrates and products, hormones and mediators and nerve densities exist which are important not only for the short-term regulation of carbohydrate metabolism but also for the long-term regulation of zonal gene expression. The specialization of periportal and perivenous hepatocytes in carbohydrate metabolism has been well characterized. In vivo evidence is provided by the complex metabolic situation termed the 'glucose paradox' and by zonal flux differences calculated on the basis of the distribution of enzymes and metabolites. In vitro evidence is given by the different flux rates determined with classical invasive techniques, e.g. in periportal-like and perivenous-like hepatocytes in cell culture, in periportal- and perivenous-enriched hepatocyte populations and in perfused livers during orthograde and retrograde flow, as well as with noninvasive techniques using miniature oxygen electrodes, e.g. in livers perfused in either direction. Differences of opinion in the interpretation of studies with invasive and noninvasive techniques by the authors are discussed. The declining gradient in oxygen concentrations, the decreasing glucagon/insulin ratio and the different innervation could be important factors in the zonal expression of the genes of carbohydrate-metabolizing enzymes. While it is clear that the hepatocytes sense the glucagon/insulin gradients via the respective hormone receptors, it is not known how they sense different oxygen tensions; the O2 sensor may be an oxygen-binding heme protein. The zonal separation of glucose release and uptake appears to be important for the liver to operate as a 'glucostat'. Thus, zonation of carbohydrate metabolism develops gradually during the first weeks of life, in part before and in part with weaning, when (in rat and mouse) the fat- and protein-rich but carbohydrate-poor nutrition via milk is replaced by carbohydrate-rich food. Similarly, zonation of carbohydrate metabolism adapts to longer lasting alterations in the need of a 'glucostat', such as starvation, diabetes, portocaval anastomoses or partial hepatectomy.

The zonal distribution of phosphoenolpyruvate carboxykinase (PCK) and tyrosine aminotransferase (TAT) mRNA in liver was studied by in situ hybridization with radiolabelled cRNA probes and the abundance of PCK and TAT mRNA was quantified by Northern blot analysis of total RNA with biotinylated cRNA probes. Livers were taken from rats during a normal 12 h day/night rhythm, when they had access to food only during the dark period from 7 pm to 7 am, or during refeeding, when they had access to food after having been starved for 60 h. 1. Daily feeding rhythm: High levels of PCK mRNA were distributed mainly in the periportal and intermediate zone during the fasting period at noon and 6 pm. Feeding caused a rapid decrease in PCK mRNA level and a restriction of PCK mRNA localization to the periportal area within the first 2 h. No further alterations were observed during the following hours of the feeding period. TAT mRNA was distributed also in the periportal and intermediate zone during the fasting period. Feeding first reduced the mRNA level without changing the distribution pattern. Then towards the end of the feeding period TAt mRNA increased again to half-maximal levels and became restricted mainly to the periportal area. 2. Starvation-refeeding cycle: High amounts of PCK mRNA as well as of TAT mRNA were localized predominantly in the periportal and intermediate zone after 60 h of starvation. PCK and TAT mRNA both decreased markedly during the first 2 h of refeeding and then remained almost constant. Whereas the alterations in the overall abundance of the two mRNAs were similar, the distribution patterns of both mRNAs differed. While PCK mRNA became more and more restricted to a small area of periportal cells towards the end of refeeding, TAT mRNA was first evenly distributed in the periportal and perivenous area with higher amounts in the intermediate zone and then again was predominantly located in the periportal area. The present data indicate that the predominant periportal localization of PCK and TAT activity and enzyme protein is regulated mainly at the pretranslational level.

The inhibitory action of insulin and proinsulin on basal and glucagon-activated glycogenolysis was studied in cultured rat hepatocytes containing [14C]glycogen. Insulin or proinsulin given as sole hormones in the presence of 5 mM glucose decreased basal release of [14C]glucose from [14C]glycogen to 20%. Half-maximal effective concentration of insulin was approximately 0.15 nM and of proinsulin was approximately 5 nM. Inhibition of [14C]lactate release from [14C]glycogen required slightly higher hormone concentrations with a similar difference in potency for insulin and proinsulin. The glucagon-stimulated release of [14C]glucose was completely blocked by insulin or proinsulin with half-maximal effective concentrations of approximately 0.2 and approximately 8 nM, respectively. In contrast, release of [14C]lactate in the presence of glucagon was increased slightly by insulin and proinsulin. Basal and glucagon-activated phosphorylase activity was inhibited by approximately 50% in a dose-dependent manner by both hormones, with differences in potency similar to those for the inhibition of glycogenolysis. These data point to a direct regulatory role of insulin in the control of hepatic glycogen breakdown even when acting as sole hormone. The results do not support the notion of a preferential inhibitory potency of proinsulin on hepatic glycogenolysis.

Short-term effects of human proinsulin on metabolic rates and its long-term action on enzyme induction were studied in primary cultures of rat hepatocytes and in the perfused rat liver, and compared with the effects of bovine insulin. In the perfused rat liver, proinsulin decreased the glucagon-dependent increase of glycogenolysis. The action of 0.5 nM glucagon was almost completely suppressed by 100 nM proinsulin. Proinsulin and insulin showed similar potency. In cultured rat hepatocytes, proinsulin stimulated glycolysis up to fivefold with a half-maximal effective dose of 30 nM. Proinsulin induced the key glycolytic enzymes glucokinase and pyruvate kinase by twofold and antagonized the glucagon-dependent induction of phosphoenolpyruvate carboxykinase with a half-maximal effective dose at 3 nM. For the effects in cultured hepatocytes, about 100-fold higher concentrations of proinsulin than of insulin were required.

During the first 72 h after 67% partial hepatectomy of female Wistar rats (160 g) the specific activities [mumol X min-1 X (g liver)-1] of the glucogenic glucose-6-phosphatase and fructose-bisphosphatase and of the glycolytic hexokinase and 6-phosphofructokinase remained essentially constant. However, the activity of the glycolytic pyruvate kinase (L- plus M2-type) was decreased slightly and that of glucokinase was decreased markedly to below 30%, while the glucogenic phosphoenolpyruvate carboxykinase was increased to over 200%. Between 10 and 40 h after partial hepatectomy, when the proliferation started in the periportal area, a shift of the glucogenic glucose-6-phosphatase-rich zone from its normal periportal to an intermediate or even perivenous position was observed histochemically. After 48 h, when the proliferation was no longer restricted to the periportal zone, the normal glucose-6-phosphatase zonation (as before partial hepatectomy) was restored. Glycogen was degraded rapidly during the first 4 h after operation; it was later repeatedly resynthesized and degraded in correlation with the feeding rhythm of the animals. The zonation of glycogen metabolism was in accord with the observed zonation of glucose-6-phosphatase.

FEBS LettersVolume 76, Issue 2 p. 226-230 Full-length articleFree Access Heterogeneous distribution of glucose-6-phosphatase in microdissected periportal and perivenous rat liver tissue Norbert Katz, Norbert Katz Biochemisches Institut, Albert-Ludwigs-Universität, D-7800 Freiburg, FRGSearch for more papers by this authorHarald F. Teutsch, Harald F. Teutsch Anatomisches Institut, Albert-Ludwigs-Universität, D-7800 Freiburg, FRGSearch for more papers by this authorDieter Sasse, Dieter Sasse Anatomisches Institut, Albert-Ludwigs-Universität, D-7800 Freiburg, FRGSearch for more papers by this authorKurt Jungermann, Kurt Jungermann Biochemisches Institut, Albert-Ludwigs-Universität, D-7800 Freiburg, FRGSearch for more papers by this author Norbert Katz, Norbert Katz Biochemisches Institut, Albert-Ludwigs-Universität, D-7800 Freiburg, FRGSearch for more papers by this authorHarald F. Teutsch, Harald F. Teutsch Anatomisches Institut, Albert-Ludwigs-Universität, D-7800 Freiburg, FRGSearch for more papers by this authorDieter Sasse, Dieter Sasse Anatomisches Institut, Albert-Ludwigs-Universität, D-7800 Freiburg, FRGSearch for more papers by this authorKurt Jungermann, Kurt Jungermann Biochemisches Institut, Albert-Ludwigs-Universität, D-7800 Freiburg, FRGSearch for more papers by this author First published: April 15, 1977 https://doi.org/10.1016/0014-5793(77)80157-9Citations: 76AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References 1 T.B. Lee, V.K. Vance, G.F. Cahill Jr., Amer. J. Physiol., 203, (1962), 27– 10.1152/ajplegacy.1962.203.1.27 CASPubMedWeb of Science®Google Scholar 2 M.C. Scrutton, M.F. Utter, Ann. Rev. Biochem., 37, (1968), 249– 10.1146/annurev.bi.37.070168.001341 CASWeb of Science®Google Scholar 3 J.H. Exton, Metabolism, 21, (1972), 947– 10.1016/0026-0495(72)90028-5 Web of Science®Google Scholar 4 W.G. Guder, U. Schmidt, Proc. 6th Int. Cong. Nephrology (1976), Karger Verlag Basel Google Scholar 5 W.G. Guder, U. Schmidt, Z. Physiol. Chem., 355, (1974), 273– 10.1515/bchm2.1974.355.1.273 CASPubMedWeb of Science®Google Scholar 6 U. Schmidt, I. Marosvari, U.C. Dubach, FEBS Lett., 53, (1975), 26– 10.1016/0014-5793(75)80673-9 CASPubMedWeb of Science®Google Scholar 7 K. Jungermann, N. Katz, D. Sasse, J.M. Tager H.D. Söling J.R. Williamson Use of Isolated Liver Cells and Kidney Tubules in Metabolic Studies (1976), North-Holland Amsterdam 404– Google Scholar 8 N. Katz, K. Jungermann, Z. Physiol. Chem., 357, (1976), 359– 10.1515/bchm2.1976.357.1.359 CASPubMedWeb of Science®Google Scholar 9 D. Sasse, N. Katz, K. Jungermann, FEBS Lett., 57, (1975), 83– 10.1016/0014-5793(75)80157-8 CASPubMedWeb of Science®Google Scholar 10 A.M. Rappaport, Klin. Wschr., 38, (1960), 561– 10.1007/BF01483191 CASPubMedWeb of Science®Google Scholar 11 O.H. Lowry, I.V. Passonneau, A Flexible System of Enzymatic Analysis (1972), Academic Press New York, San Francisco, London PubMedGoogle Scholar 12 M. Wachstein, M. Meisel, J. Histochem. Cytochem., 4, (1956), 592– 10.1177/4.6.592 Web of Science®Google Scholar 13 A. Goebel, H. Puchtler, Virchows Arch. Path. Anat., 326, (1955), 312– 10.1007/BF00954773 CASPubMedGoogle Scholar 14 Duve C. De, B.C. Pressman, R. Gianetto, R. Wattiaux, F. Appelman, Biochem. 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Karl, R. Schwarz, J. Histochem. Cytochem., 7, (1959), 237– 10.1177/7.4.237 CASPubMedWeb of Science®Google Scholar 23 F.A. Welsh, J. Histochem. Cytochem., 20, (1972), 107– 10.1177/20.2.107 CASPubMedWeb of Science®Google Scholar 24 D. Chiquoine, J. Histochem. Cytochem., 1, (1953), 429– 10.1177/1.6.429 CASPubMedWeb of Science®Google Scholar 25 K. Jungermann, N. Katz, H. Teutsch, D. Sasse, R.G. Thurman J.R. Williamson H. Drott B. Chance Alcohol and aldehydes metabolizing systems (1977), Academic Press New York in press Google Scholar Citing Literature Volume76, Issue2April 15, 1977Pages 226-230 ReferencesRelatedInformation

AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References 1 T.B. Lee, V.K. Vance, G.F. Cahill jr., Am. J. Physiol., 203, (1962), 27– 2 M.C. Scrutton, M.F. Utter, Arm. Rev. Biochem., 37, (1968), 249– 3 J.H. Exton, Metabolism, 21, (1972), 947– 4 N. Katz, K. Jungermann, Z. Physiol. Chem., 357, (1976), 359– 5 D. Sasse, N. Katz, K. Jungermann, FEBS Lett., 57, (1975), 83– 6 D. Sasse, Histochemistry, 45, (1975), 237– 7 K. Jungermann, N. Katz, D. Sasse, J.M. Tager H.D. Söling J.R. Williamson Use of Isolated Liver Cells and Kidney Tubules in Metabolic Studies (1976), North-Holland Amsterdam 404– 8 A.M. Rappaport, Klin. Wschr., 38, (1960), 561– 9 W.G. Guder, U. Schmidt, Proc. 6th Int. Cong. Nephrology (1976), Karger Verlag Basel 10 W.G. Guder, U. Schmidt, Z. Physiol. Chem., 355, (1974), 273– 11 U. Schmidt, I. Marosvari, U.C. Dubach, FEBS Lett., 53, (1975), 26– 12 O.H. Lowry, I.V. Passonneau, A flexible system of enzymatic analysis (1972), Academic Press New York, San Francisco, London 13 W.G. Guder, U. Schmidt, B. Funk, J. Weis, S. Pürshel, Z. Physiol. Chem., 357, (1976), 1793– 14 N. Katz, H.F. Teutsch, D. Sasse, K. Jungermann, FEBS Lett., 76, (1977), 226– 15 M. Wachstein, M. Meisel, J. Histochem. Cytochem., 4, (1956), 592– 16 K. Taketa, B.M. Pogell, J. Biol. Chem., 240, (1965), 651– 17 D.G. Walker, Essays Biochem., 2, (1966), 33– 18 H.V. Werner, J.C. Bartley, M.N. Berry, Biochem. J., 130, (1972), 1153– 19 J.M. Wimhurst, K.L. Manchester, Biochem. J., 134, (1973), 143– 20 R.E. Shank, G. Morrison, C.H. Cheng, I. Karl, R. Schwarz, J. Histochem. Cytochem., 7, (1959), 237– 21 F.A. Welsh, J. Histochem. Cytochem., 20, (1972), 107– 22 J.M. Wimhurst, K.L. Manchester, Biochem. J., 120, (1970), 95– 23 S. Pontremoli, E. Melloni, F. Salamino, Flora A. de, B.L. Horecker, Proc. Natl. Acad. Sci. USA, 71, (1974), 1776– 24 M. Salas, E. Vinuela, A. Sols, J. Biol. Chem., 238, (1963), 3535– 25 C. Sharma, R. Manjeshwar, S. Weinhouse, J. Biol. Chem., 238, (1963), 3840– 26 L. Clark-Turri, J. Penaranda, E. Rabajille, H. Niemeyer, FEBS Lett., 41, (1974), 342– 27 K. Jungermann, N. Katz, H. Teutsch, D. Sasse, R.G. Thurman J.R. Williamson H. Drott B. Chance Alcohol and aldehyde metabolizing systems (1977), Academic Press New York in press Citing Literature Volume83, Issue2November 15, 1977Pages 272-276 ReferencesRelatedInformation

FEBS LettersVolume 69, Issue 1-2 p. 23-26 Full-length articleFree Access Perinatal development of the metabolic zonation of hamster liver parenchyma Norbert Katz, Norbert Katz Biochemisches Institut, Albert-Ludwigs-Universität, D 7800 Freiburg im Breisgau, GermanySearch for more papers by this authorHarald F. Teutsch, Harald F. Teutsch Anatomisches Institut, Albert-Ludwigs-Universität, D 7800 Freiburg im Breisgau, GermanySearch for more papers by this authorKurt Jungermann, Kurt Jungermann Biochemisches Institut, Albert-Ludwigs-Universität, D 7800 Freiburg im Breisgau, GermanySearch for more papers by this authorDieter Sasse, Dieter Sasse Anatomisches Institut, Albert-Ludwigs-Universität, D 7800 Freiburg im Breisgau, GermanySearch for more papers by this author Norbert Katz, Norbert Katz Biochemisches Institut, Albert-Ludwigs-Universität, D 7800 Freiburg im Breisgau, GermanySearch for more papers by this authorHarald F. Teutsch, Harald F. Teutsch Anatomisches Institut, Albert-Ludwigs-Universität, D 7800 Freiburg im Breisgau, GermanySearch for more papers by this authorKurt Jungermann, Kurt Jungermann Biochemisches Institut, Albert-Ludwigs-Universität, D 7800 Freiburg im Breisgau, GermanySearch for more papers by this authorDieter Sasse, Dieter Sasse Anatomisches Institut, Albert-Ludwigs-Universität, D 7800 Freiburg im Breisgau, GermanySearch for more papers by this author First published: October 15, 1976 https://doi.org/10.1016/0014-5793(76)80645-XCitations: 38AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References 1 M.C. Scrutton, M.F. Utter, Ann. Rev. Biochem., 37, (1968), 249– 2 M. Wachstein, M. Meisel, Am. J. Clin. Pathol., 27, (1957), 13– 3 A.B. Novikoff, J. Histochem. Cytochem., 7, (1959), 240– 4 A.D. Chiquoine, J. Histochem. Cytochem., 1, (1953), 429– 5 D. Sasse, N. Katz, K. Jungermann, FEBS Lett., 57, (1975), 83– 6 K. Jungermann, N. Katz, D. Sasse, J.M. Tager H.D. Söling J.R. Williamson Use of Isolated Liver Cells and Kidney Tubules in Metabolic Studies 404, (1976), North-Holland Publishing Company Amsterdam 7 N. Katz, K. Jungermann, Z. Phys. Chem., 357, (1976), 359– 8 H.B. Burch, O.H. Lowry, A.M. Kuhlman, J. Skerjance, E.J. Diamant, S.R. Lowry, Dippe P. Von, J. Biol. Chem., 238, (1963), 2267– 9 R.G. Vernon, D.G. Walker, Biochem. J., 106, (1968), 321– 10 M.C. Ward, Am. J. Anat., 82, (1948), 231– 11 D.D. Hagerman, C.A. Villee, Physiol. Rev., 40, (1960), 313– 12 F. Dieterlen, Z. Tierpsychol., 16, (1959), 47– 13 H.A. Dymszy, D.M. Czajka, S.A. Miller, J. Nutr., 84, (1964), 100– Citing Literature Volume69, Issue1-2October 15, 1976Pages 23-26 ReferencesRelatedInformation

Hepatocytes were isolated from fed rats with glucose and insulin and freom fasted rats with glucagon in all media in an attempt to obtain cells which might be fixed preferentially in either the glycolytic or gluconeogenic state. When tested enzymatically, both "fed" and fasted" cells catalyzed glucose formation from lactate (gluconeogenesis) and lactate formation from fructose (fructolysis); lactate formation from glucose may have occurred in "fed" cells. Thus it was impossible, at least in the C3 part of the metabolic pathways between triosephosphate and pyruvate, to fix the hepatocytes in either metabolic state. The shift from glycolysis to gluconeogenesis could be investigated for the C3 part in "fasted" cells with fructose as the glycolytic and lactate as the gluconeogenic substrate. Lactate was first formed from fructose and later reutilized to a large extent. This reconsumption was blocked by the gluconeogenesis inhibitor quinolinate, both when tested enzymatically and radiochemically. Thus fructolysis was shifted to lactate gluconeogenesis. This shift at the assumed phosphoenolpyruvate/pyruvate cycle was autoregulatory, i.e. dependent on substrates and independent of circulating horomes. Maximal velocities and half saturating concentrations were determined for fructose and for lactate as substrates. The kinetic data obtained, especially the sigmoidal pattern of fructolysis, could nicely explain phenomenologically the rather sudden slow-down of lactate production and the shift to lactate consumption. The levels of the metabolites ATP, ADP, AMP, fructose bisphosphate and alanine, which control the enzymes of the assumed phosphoenolypyruvate/pyruvate cycle, were determined in the cytosol and in the mitochondria before and after the shift from fructose glycolysis to lactate gluconeogenesis. The changes observed could not explain the shift. Experiments with [14C] fructose plus unlabelled lactate and reciprocally, with unlabelled fructose plus [14C] lactate, clearly reveled that within the C3 part, glycolysis and gluconeogenesis were catalyzed simultaneously. The simultaneity of and the shift between fructolysis and gluconeogenesis by the liver cell suspension can best be explained by assuming two metabolically different types of hepatocytes rather than one type of hepatocyte with metabolically equal or different cell compartment. In vivo, the different types of hepatocytes would form a gluconeogenic and a glycolytic zone within the liver parenchyma. Since, under normal conditions, the size of these metabolic zones should remain unaltered, the shift from net glycolysis to net gluconeogenesis would be dependent primarily on substrate concentrations (autoregulation).

ATPase (ATP phosphohydrolase, EC 3.6.1.3) was detected in the membrane fraction of the strict anaerobic bacterium, Clostridium pasteurianum. About 70% of the total activity was found in the particulate fraction. The enzyme was Mg2+ dependent; Co2+ and Mn2+ but not Ca2+ could replace Mg2+ to some extent; the activation by Mg2+ was slightly antagonized by Ca2+. Even in the presence of Mg2+, Na+ or K+ had no stimulatory effect. The ATPase reaction was effectively inhibited by one of its products, ADP, and only slightly by the other product, inorganic phosphate. Of the nucleoside triphosphates tested ATP was hydrolyzed with highest affinity ([S]0.5 v = 1.3 mM) and maximal activity (120 U/g). The ATPase activity could be nearly completely solubilized by treatment of the membranes with 2 M LiCl in the absence of Mg2+. Solubilization, however, led to instability of the enzyme. The clostridial solubilized and membrane-bound ATPase showed different properties similar to the "allotopic" properties of mitochondrial and other bacterial ATPases. The membrane-bound ATPase in contrast to the soluble ATPase was sensitive to the ATPase inhibitor dicyclohexylcarbodiimide (DCCD). DCCD, at 10(-4) M, led to 80% inhibition of the membrane-bound enzyme; oligomycin ouabain, or NaN3 had no effect. The membrane-bound ATPase could not be stimulated by trypsin pretreatment. Since none of the mono- or divalent cations had any truly stimulatory effect, and since a pH gradient (interior alkaline), which was sensitive to the ATPase inhibitor DCCD, was maintained during growth of C. pasteurianum, it was concluded that the function of the clostridial ATPase was the same as that of the rather similar mitochondrial enzyme, namely H+ translocation. A H+-translocating, ATP-consuming ATPase appears to be intrinsic equipment of all prolaryotic cells and as such to be phylogenetically very old; in the course of evolution the enzyme might have been developed to a H+-(re)translocating, ATP-forming ATPase as probably realized in aerobic bacteria, mitochondria and chloroplasts.