Subcellular Localization of Folate and Effect of Methotrexate on the Incorporation of Radioactive Folic Acid into Guinea-Pig Liver Folate

1972 ◽  
Vol 43 (6) ◽  
pp. 815-822 ◽  
Author(s):  
R. Corrocher ◽  
A. V. Hoffbrand
Keyword(s):  
Folic Acid ◽  
Guinea Pig ◽  
Subcellular Localization ◽  
Subcellular Distribution ◽  
Mammalian Cells ◽  
Pig Liver ◽  
Pteroylglutamic Acid ◽  
Tetrahydrofolic Acid ◽  
Guinea Pig Liver ◽  
Liver Folate

1. The subcellular distribution of endogenous folate and of injected [3H]folic acid has been studied in guinea-pig liver. 2. Endogenous folate was found to be concentrated in the mitochondrial and cell-sap fractions. 3. At 1 h after injection, labelled folic acid (pteroylglutamic acid) was concentrated in the microsomes (where it is possibly reduced to tetrahydrofolic acid). 4. At all subsequent times after injection of labelled pteroylglutamic acid (4, 24 and 84 h) radioactivity was concentrated in mitochondria and cell sap and it is, therefore, likely that conjugation of glutamates to form pteroylpolyglutamates occurs in one or both of these subcellular fractions in mammalian cells. 5. Methotrexate-treated animals converted at least some labelled pteroylglutamic acid into non-reduced pteroyl di-, tri- and poly-glutamic acids by 4 h after the injection. 6. Reduction of pteroylglutamic acid is, therefore, not essential for pteroylpolyglutamate formation in liver cells. 7. Methotrexate blocks the reduction of pteroyl di-, tri- and poly-glutamic acids, as well as of pteroylglutamic acid.

Composition of Pteroylpolyglutamates (Conjugated Folates) in Guinea-Pig Liver and Their Formation from Folic Acid

1972 ◽  
Vol 43 (6) ◽  
pp. 799-813 ◽  
Author(s):  
R. Corrocher ◽  
B. K. Bhuyan ◽  
A. V. Hoffbrand
Keyword(s):  
Folic Acid ◽  
Guinea Pig ◽  
Lactobacillus Casei ◽  
Deae Cellulose ◽  
Microbiological Assay ◽  
Pig Liver ◽  
Ion Exchange Column ◽  
Pteroylglutamic Acid ◽  
Guinea Pig Liver ◽  
Liver Folate

1. The composition of guinea-pig liver folates and the biochemical route of formation of liver folates from injected tritium-labelled pteroylglutamic acid (folic acid) have been studied. 2. Endogenous folate was measured by microbiological assay with Lactobacillus casei and Streptococcus faecalis, with and without deconjugation of whole liver pteroylpolyglutamates (conjugated folates). Individual folate compounds were identified by microbiological assay after fractionation of liver folates by DEAE cellulose ion-exchange column chromatography. 3. Liver folate in the guinea-pig consists of about 84–87% reduced pteroylpolyglutamates with more than three glutamate moieties/molecule, about 12–15% reduced pteroyltriglutamates, about 1% reduced pteroyldiglutamates and only traces of reduced pteroylmonoglutamates. 4. About 53% of the liver folate consists of methylated derivatives. 5. Injected pteroylglutamic acid was first rapidly reduced and formylated or methylated. Glutamate moieties were then added, probably singly, to form di-, tri- and poly-glutamates. This was a relatively slow process with a hold-up at the triglutamate stage. 6. The proportion of the labelled pteroylglutamic acid in the polyglutamate form approximated to the proportion of endogenous folates in this form after 3–4 days. 7. The amount of radioactive folate in the liver increased progressively from 1 to 84 h after injection of a standard amount of radioactive pteroylglutamic acid.

Die Bedeutung der Homogenisationsart und -intensität für die Größe und Konstanz der Sauerstoffaufnahme von Meerschweinchen-Leberhomogenat / The Influence of Mode and Intensity of Homogenization on the Absolute Value and Stability of Oxygen Consumption of Guinea Pig Liver Homogenates

1977 ◽  
Vol 32 (11-12) ◽  
pp. 908-912 ◽  
Author(s):  
H. J. Schmidt ◽  
U. Schaum ◽  
J. P. Pichotka
Keyword(s):  
Oxygen Uptake ◽  
Guinea Pig ◽  
Measuring Time ◽  
Pig Liver ◽  
Absolute Value ◽  
Modified Method ◽  
Simultaneous Measurements ◽  
Liver Homogenates ◽  
The Absolute ◽  
Guinea Pig Liver

Abstract The influence of five different methods of homogenisation (1. The method according to Potter and Elvehjem, 2. A modification of this method called Potter S, 3. The method of Dounce, 4. Homogenisation by hypersonic waves and 5. Coarce-grained homogenisation with the “Mikro-fleischwolf”) on the absolute value and stability of oxygen uptake of guinea pig liver homogenates has been investigated in simultaneous measurements. All homogenates showed a characteristic fall of oxygen uptake during measuring time (3 hours). The modified method according to Potter and Elvehjem called Potter S showed reproducible results without any influence by homogenisation intensity.

Precision-cut Guinea-pig Liver Slices as a Tool for Studying the Toxicity of Volatile Anaesthetics

1990 ◽  
Vol 18 (1_part_1) ◽  
pp. 191-199
Author(s):  
Hanan N. Ghantous ◽  
Jeanne Fernando ◽  
Scott E. Morgan ◽  
A. Jay Gandolfi ◽  
Klaus Brandel
Keyword(s):  
Guinea Pig ◽  
Rank Order ◽  
Normal Liver ◽  
Liver Slice ◽  
Volatile Anaesthetics ◽  
Pig Liver ◽  
Liver Slices ◽  
Guinea Pig Liver ◽  
Krebs Henseleit Buffer

Cultured precision-cut liver slices retain normal liver architecture and physiological biochemical functions. Hartley male guinea-pig liver slices have proven to be a good model for studying the biotransformation and toxicity of halothane. This system was used to evaluate the biotransformation and toxicity of different volatile anaesthetics (halothane, enflurane, isoflurane and sevoflurane), and compare their effects to those of new anaesthetics (desflurane). Liver slices (250–300μm thick) were incubated in sealed roller vials, containing Krebs Henseleit buffer at 37°C under 95% O2:5% CO2 atmosphere. Volatile anaesthetics were delivered by volatilisation after pre-incubation for 1 hour to produce a constant concentration in the medium. Production of the metabolites, trifluroacetic acid and fluoride ion, was measured. Intracellular potassium ion content, protein synthesis and secretion were determined as indicators of viability of the slices. The rank order of biotransformation of anaesthetics by the liver slices was halothane >sevoflurane>isoflurane and enflurane>desflurane. The rank order of hepatotoxicity of these anaesthetics was halothane>isoflurane and enflurane>sevoflurane and desflurane. Halothane is the anaesthetic which is metabolised furthest and has the most toxic effect, while desflurane is the least metabolised anaesthetic and has the least toxicity. This in vitro cultured precision-cut liver slice system appears to be suitable for studying the biotransformation of volatile anaesthetics and correlating its role in the resulting toxicity.

scholarly journals Exolytic hydrolysis of toxic plant glucosides by guinea pig liver cytosolic beta-glucosidase.

1992 ◽  
Vol 267 (20) ◽  
pp. 14027-14032
Author(s):  
V Gopalan ◽  
A Pastuszyn ◽  
W R Galey ◽  
R.H. Glew
Keyword(s):  
Guinea Pig ◽  
Pig Liver ◽  
Beta Glucosidase ◽  
Toxic Plant ◽  
Hydrolysis Of ◽  
Guinea Pig Liver

scholarly journals THE REDUCTION OF l-XYLULOSE TO XYLITOL BY GUINEA PIG LIVER MITOCHONDRIA

1956 ◽  
Vol 221 (2) ◽  
pp. 697-709 ◽  
Author(s):  
Oscar Touster ◽  
V.H. Reynolds ◽  
Ruth M. Hutcheson
Keyword(s):  
Guinea Pig ◽  
Liver Mitochondria ◽  
Pig Liver ◽  
Guinea Pig Liver
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