scholarly journals Studies on the metabolism of oestrone sulphate. Comparative perfusions of oestrone and oestrone sulphate through isolated rat livers

1977 ◽  
Vol 166 (3) ◽  
pp. 363-371 ◽  
Author(s):  
Michael Höller ◽  
Wilhelm Grochtmann ◽  
Mechthild Napp ◽  
Heinz Breuer
Keyword(s):  
Liver Cell ◽  
Liver Tissue ◽  
Glucuronic Acid ◽  
First Passage ◽  
Large Reservoir ◽  
Isolated Rat Liver ◽  
Oestrone Sulphate ◽  
Rat Livers ◽  
Hydroxy Steroid ◽  
Isolated Rat

The metabolism of [4-14C]oestrone and of [6,7-3H2]oestrone sulphate was studied during cyclic perfusion and once-through perfusion of the isolated rat liver. The following results were obtained. 1. As shown by once-through perfusion, the two steroids are metabolized differently during the first passage through the organ. [4-14C]Oestrone was taken up by the liver and partly delivered as oestradiol-17β and oestriol into the medium. After uptake of [6,7-3H2]oestrone sulphate, only oestrone, liberated by hydrolysis, was delivered into the medium; no oestradiol-17β or oestriol could be detected in the medium after one passage through the organ. This indicates that intracellular oestrone, which was taken up as such, and oestrone, which derived from intracellular hydrolysis, may be metabolized in different compartments of the liver cell. 2. The results of the cyclic perfusion showed that intracellular oestrone is preferentially conjugated with glucuronic acid, and subsequently excreted into the bile. Intracellular oestrone sulphate is preferably reduced to oestradiol sulphate, thus indicating that oestrone sulphate is a better substrate for the 17β-hydroxy steroid oxidoreductase than is oestrone. 3. Albumin-bound oestrone sulphate acts as a large reservoir, and in contrast with free oestrone is protected from enzyme attack by its strong binding to albumin. 4. Oestrone sulphate is partly converted into the hormonally active oestrone by liver tissue. This suggests that liver not only inactivates oestrogens, but also provides the organism with oestrone, which is subsequently readily taken up by other organs.

Simultaneous perfusion of [4-14C]oestriol and [6,9-3H2]oestriol 16α-monoglucuronide through the isolated rat liver

1982 ◽  
Vol 100 (1) ◽  
pp. 57-62 ◽  
Author(s):  
M. Höller ◽  
H. Weber ◽  
H. Breuer
Keyword(s):  
Rat Liver ◽  
Glucuronic Acid ◽  
Small Extent ◽  
Isolated Rat Liver ◽  
Metabolic Reactions ◽  
Biliary Metabolite ◽  
Rat Livers ◽  
Isolated Rat

Abstract. Equimolar concentrations of [4-14C]oestriol and [6,9-3H2]oestriol 16α-monoglucuronide were simultaneously perfused through isolated rat livers. Oestriol was hydroxylated to 2-hydroxyoestriol and 6ξ-hydroxyoestriol; 2-hydroxyoestriol was further methylated to 2-methoxyoestriol. Oxidoreduction of oestriol led to the formation of 16α-hydroxyoestrone, 16-oxooestradiol-17β and 16-epioestriol. In addition, two dehydroxylation products, namely oestrone and oestradiol-17β were found. The metabolites formed from oestriol were partly conjugated to monoglucuronides, monosulphates and sulphoglucuronides. About 80% of the oestriol perfused was hydroxylated at C-atom 2. Most of the 2-hydroxyoestriol formed was either methylated (about 37%) or sulphated (about 55%). Only small amounts (less than 2%) of the catecholoestrogens formed were methylated as well as sulphated. The 2-hydroxyoestriol monosulphates accumulated in the liver. After their conjugation with glucuronic acid, the double conjugates formed were immediately excreted into the bile. In fact, 2-hydroxyoestriol 16α-monoglucuronide 2(3?)-monosulphate comprised by far the main biliary metabolite of [4-14C]oestriol, followed by oestriol 16α-monoglucuronide and 2-methoxyoestriol 16α-monoglucuronide. No tritiated sulphoglucuronides were detected, thus indicating that the monosulphates are the immediate precursors of the double conjugates. [6,9-3H2]Oestriol 16α-monoglucuronide was metabolised only to a small extent. After its uptake into the liver more than 90% of this conjugate was secreted unchanged into the bile. The remaining part was hydrolysed; the oestriol liberated followed the same metabolic reactions as those found for [4-14C]oestriol. This indicates that the 16α-glucuronide of oestriol is not metabolised to any appreciable extent.

Ultrastructural changes in isolated rat liver perfused with cyclic heptapeptide toxins from norwegian freshwater cyanobacteria (blue-green algae)

1987 ◽  
Vol 45 ◽  
pp. 858-859
Author(s):  
A.S. Dabholkar ◽  
W.W. Carmichael ◽  
K. Berg ◽  
J. Wyman
Keyword(s):  
Ultrastructural Changes ◽  
Sprague Dawley ◽  
Isolated Rat Liver ◽  
Blue Green Algae ◽  
Sprague Dawley Rats ◽  
Cyclic Heptapeptide ◽  
Intracellular Changes ◽  
Oscillatoria Agardhii ◽  
Rat Livers ◽  
Isolated Rat

Intracellular changes in the hepatocytes of isolated rat livers perfused with cyclic heptapeptide toxins are described. The toxins used are 1) -Ala-Leu- β-methyl isoAsp-Arg-ADDA-isoGlu-mdha (M.W. 944) from Microcystis aeruginosa- Lake Akersvatn, Norway; 2) -Ala-Arg-isoAsp-Arg-ADDA-isoGlu-mdha (M.W. 1023) from Oscillatoria agardhii var. - Lake Kolbatnvatn, Norway; 3) -Ala-Arg-isoAsp-Arg-ADDA-isoGlu-dha (M.W. 1009) from Oscillatoria agardhii var. isothrix - Lake Froylandsvatn, Norway. Approximate LD intraperitoneal mouse for the toxins is 50, 500 and 1000 μg/kg respectively.Livers were removed from male Sprague Dawley rats and perfused for 15 min with a blood-free perfusate (50 ml) followed by 60 min with perfusate containing i) 25, 50, or 200 μg of M. aeruginosa toxin ii) 50, 250, 500 or 1000 μg of O. agardhii var. toxin and iii) 1000, 2000, 2500 or 5000 μg of O. agardhii var. isothrix toxin. Control livers were perfused for 75 min with the blood-free perfusate.

Titration of Rat Liver with Digitonin: a Well Defined Short Term Damage of Cellular Metabolism

1981 ◽  
Vol 36 (9-10) ◽  
pp. 880-883 ◽  
Author(s):  
Stefan Postius ◽  
Dieter Platt
Keyword(s):  
Lactate Dehydrogenase ◽  
Rat Liver ◽  
Liver Cell ◽  
Plasma Membranes ◽  
Short Term ◽  
Isolated Rat Liver ◽  
Physiological Conditions ◽  
Cell Plasma ◽  
Molecular Compounds ◽  
Isolated Rat

Abstract Carefully performed pulse titration of the isolated rat liver in the course of continuous erythro­ cyte free perfusion with small amounts of digitonin causes a short term perm eability of liver cell plasma membranes with concomitant short lived release of intracellular low or high molecular compounds such as ATP or lactate dehydrogenase. Gluconeogenesis from lactate being completely inhibited during this period restores w ithin about one m inute up to a level that depends on the am ount of perfused digitonin. The described experimental m odel is suggested to be useful for the measurement of cytoplasmic m etabolites under physiological conditions. It moreover offers the possibility to im port foreign substances into liver cells th at normally do not penetrate liver cell plasma membranes.

scholarly journals The metabolism of dipotassium 2-hydroxy-5-nitrophenyl [35S]sulphate, a substrate for lysosomal arylsulphatases A and B

1967 ◽  
Vol 105 (3) ◽  
pp. 1003-1012 ◽  
Author(s):  
T. G. Flynn ◽  
K S Dodgson ◽  
G M Powell ◽  
F A Rose
Keyword(s):  
Bile Duct ◽  
Kidney Function ◽  
Intraperitoneal Injection ◽  
Chromogenic Substrate ◽  
Metabolic Fate ◽  
Isolated Rat Liver ◽  
Anaesthetized Rats ◽  
Free Ranging ◽  
Rat Livers ◽  
Isolated Rat

The metabolic fate of dipotassium 2-hydroxy-5-nitrophenyl [35S]sulphate ([35S]NCS), a chromogenic substrate for lysosomal arylsulphatases A and B, has been studied in rats. Intraperitoneal injection of [35S]NCS into free-ranging animals is followed by excretion of the bulk of the radioactivity in the urine within 24hr., less than 13% being eliminated as inorganic [35S]sulphate. Most of the urinary radioactivity can be accounted for as [35S]NCS, but small amounts of a labelled metabolite are also present. Experiments in which [35S]NCS was injected intravenously into anaesthetized rats with bile-duct and bladder cannulae confirm that the ester is rapidly excreted in the urine. However, small amounts of radioactivity appear in bile, mainly in the form of the metabolite detected in urine. When [35S]NCS is perfused through the isolated rat liver, about 35% of the dose is hydrolysed within 3hr. Similar results are obtained if [35S]NCS is injected into anaesthetized rats in which kidney function has been eliminated by ligature of the renal pedicles. The labelled metabolite has been isolated from bile obtained by perfusing several rat livers with blood containing a total of 100mg. of [35S]NCS. It has been identified as 2-β-glucuronosido-5-nitrophenyl [35S]sulphate. The implications of the various findings are discussed. The Appendix describes the preparation of [35S]NCS.

Effect of insulin on potassium transfer in isolated rat liver

1961 ◽  
Vol 200 (6) ◽  
pp. 1315-1319 ◽  
Author(s):  
Glenn E. Mortimore
Keyword(s):  
Rat Liver ◽  
Liver Cell ◽  
Physiological Role ◽  
Maximal Inhibition ◽  
Isolated Rat Liver ◽  
Insulin Levels ◽  
Low Concentrations ◽  
Metabolic Significance ◽  
Isolated Rat ◽  
Net Transfer

The effect of insulin on the net transfer of potassium between the isolated, cyclically perfused, fasted rat liver and the perfusate was studied. In the absence of insulin approximately 7.5% of liver potassium was lost into the serum during 60 min of perfusion. Insulin, at concentrations of 1.2 and 3.0 x 10–10 m (mol wt 6,000), inhibited this release. Maximal inhibition (93% at 10 min) was elicited with insulin levels of 1.2 x 10–9 m and greater. A comparison of liver weights at the end of the perfusions revealed that the control livers were significantly smaller than those treated with insulin. No difference in the concentration of liver potassium between these two groups was found. From these data, together with the results of liver water determinations, it was tentatively concluded that, in addition to potassium, water was also released by the liver cell. Although the metabolic significance of these shifts is not clear at present, their inhibition by low concentrations of insulin strongly suggests a physiological role for insulin in the maintenance of liver potassium and water.

Status of tRNA charging, trinucleotide acceptor sequence and tRNA nucleotidyltransferase activity in the human placenta

1976 ◽  
Vol 54 (7) ◽  
pp. 609-616 ◽  
Author(s):  
B. Suren Baliga ◽  
Christine Hubert ◽  
Alma Murphy ◽  
Felice Meadow ◽  
Peter Dourmashkin ◽  
...  
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Liver Cell ◽  
Human Placenta ◽  
Gel Electrophoresis ◽  
Periodate Oxidation ◽  
Charged State ◽  
Isolated Rat Liver ◽  
Extensive Degradation ◽  
Isolated Rat

Samples of tRNA isolated from the cell sap of full-term human placenta were found to have a low capacity for accepting amino acids in the presence of partially purified synthetase preparations made from placental or rat liver cell sap. Gel electrophoresis of placental tRNA showed that part of this could be accounted for by gross degradation. The proportion of chargeable tRNA carrying amino acids was estimated by periodate oxidation followed by stripping and then charging with labeled amino acids. Only 50% of chargeable placental tRNA was in the charged state when isolated, whereas 87% of freshly isolated rat liver tRNA was found to be charged with amino acids.A fraction prepared from placental cell sap was shown to have tRNA nucleotidyltransferase activity. When placental tRNA was incubated with this fraction and [3H]ATP or [3H]CTP, ATP was incorporated into about 12% of the tRNA molecules and CTP into 5–7%. When rat liver tRNA was used in place of placental tRNA, [3H]ATP was incorporated into less than 5% of the tRNA molecules. By using snake-venom diesterase over short periods of incubation, it was confirmed that the ATP had been incorporated terminally as AMP into the placental tRNA.These observations show that, in contrast to rat liver tRNA, tRNA prepared from human placenta is poorly charged with amino acids, many of the molecules lack the acceptor trinucleotide and there is extensive degradation beyond this stage.

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