The synthesis and degradation of rat liver and kidney fructose bisphosphatase in Vivo

1979 ◽  
Vol 194 (2) ◽  
pp. 620-631 ◽  
Author(s):  
J.George Zalitis ◽  
Henry C. Pitot
Keyword(s):  
Rat Liver ◽  
Fructose Bisphosphatase ◽  
Liver And Kidney ◽  
Synthesis And Degradation

Mechanisms of conversion of xanthine dehydrogenase to xanthine oxidase in ischemic rat liver and kidney

1988 ◽  
Vol 254 (5) ◽  
pp. G753-G760 ◽  
Author(s):  
T. G. McKelvey ◽  
M. E. Hollwarth ◽  
D. N. Granger ◽  
T. D. Engerson ◽  
U. Landler ◽  
...  
Keyword(s):  
Xanthine Oxidase ◽  
Rat Liver ◽  
Ischemia Reperfusion ◽  
Xanthine Dehydrogenase ◽  
Serum Glutamic Oxaloacetic Transaminase ◽  
Liver Model ◽  
Damage Process ◽  
Liver And Kidney ◽  
Sulfhydryl Modification

Previous studies have proposed and supported a role for the proteolytic, irreversible conversion of xanthine dehydrogenase to xanthine oxidase (XO) in postischemic injury in a wide variety of organs. A second mechanism of conversion, due to sulfhydryl modification and reversible with dithiothreitol (DTT), is potentially important but has not been well investigated. In this study rat liver and kidney were found to produce significant amounts of DTT-reversible XO during normothermic global ischemia. Formation of reversible XO precedes that of irreversible XO by approximately 0.5 h with a strong correlation (r = 0.92) existing between the rate of irreversible XO formation and the concentration of reversible XO. The formation of reversible XO is preceded by a depletion of glutathione with concentrations of glutathione during ischemia correlating (r = 0.85) with the observed concentration of reversible XO. While a large increase in the extent of liver damage occurs concurrently with conversion in an in vivo liver model of liver ischemia, an ischemia-reperfusion regimen (1 h of ischemia plus 0.5 h of reperfusion) that resulted in no conversion caused significant elevations in serum glutamic pyruvic transaminase and serum glutamic-oxaloacetic transaminase. Rats depleted of XO by tungsten dieting release 65% less enzyme after the same insult, suggesting that endogenous XO may also participate in the damage process independent of any conversion.

Studies on the Biosynthesis of Flavin Nucleotides from 2-14C-Riboflavin by Rat Liver and Kidney

1973 ◽  
Vol 51 (6) ◽  
pp. 772-782 ◽  
Author(s):  
A. G. Fazekas ◽  
T. Sandor
Keyword(s):  
Rat Liver ◽  
Flavin Adenine Dinucleotide ◽  
Total Radioactivity ◽  
Flavin Mononucleotide ◽  
Time Intervals ◽  
Adult Rats ◽  
Liver And Kidney ◽  
Rat Liver Cytosol

2-14C-Riboflavin was injected subcutaneously into young adult rats to study the biosynthesis of flavin mononucleotide (FMN) and flavin–adenine dinucleotide (FAD) in the liver and kidneys. Animals were sacrificed at different time intervals following the administration of labelled riboflavin (RF), and radioactive flavins were determined in their tissues by a newly devised method. Both tissues accumulated radioactive riboflavin rapidly and peak levels were obtained at 90 min after the injection, when over 80% of the total radioactivity of the liver was present in FAD. At this time the liver contained 17% of the injected dose of 2-14C-RF. The kidneys contained relatively high quantities of free RF due to the concentration and urinary excretion of the vitamin.Analysis of subcellular fractions of the liver of animals injected with 2-14C-RF revealed that most of the radioactivity was present in mitochondria and nuclei. The flavin nucleotides of rat liver cytosol became progressively associated with macromolecules in vivo. However, there was no significant binding of free RF by macromolecules in blood plasma or liver cytosol.Kinetic studies and incubations with liver slices indicated that RF freely diffuses into the liver cells, is rapidly converted into FAD, and becomes attached to apoenzymes. The tissue uptake of RF and FMN formation is considerably influenced by the concentration of RF present in the system, both in vivo and in vitro.

scholarly journals Effect of hypophysectomy on the rates of protein synthesis and degradation in rat liver

1979 ◽  
Vol 178 (3) ◽  
pp. 725-731 ◽  
Author(s):  
R D Conde
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Rat Liver ◽  
Protein Metabolism ◽  
Plasma Proteins ◽  
Degradation Rates ◽  
Hypophysectomized Rats ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

The effect of hypophysectomy on the protein metabolism of the liver in vivo was studied. Fractional rates of protein synthesis and degradation were determined in the livers of normal and hypophysectomized rats. Synthesis was measured after the injection of massive amounts of radioactive leucine. Degradation was estimated either as the balance between synthesis and accumulation of stable liver proteins or from the disappearance of radioactivity from the proteins previously labelled by the injection of NaH14CO3. The results indicate that: (1) hypophysectomy diminishes the capacity of the liver to synthesize proteins in vivo, mainly of those that are exported as plasma proteins; (2) livers of both normal and hypophysectomized rats show identical protein-degradation rates, whereas plasma proteins are degraded slowly after hypophysectomy.

scholarly journals Effect of a single dose of dimethylnitrosamine on biosynthesis of nucleic acid and protein in rat liver and kidney

1971 ◽  
Vol 125 (4) ◽  
pp. 943-952 ◽  
Author(s):  
B. W. Stewart ◽  
P. N. Magee
Keyword(s):  
Single Dose ◽  
Rat Liver ◽  
Sucrose Density Gradient ◽  
Polymerase Activity ◽  
Hepatic Necrosis ◽  
Deficient Diet ◽  
Morphological Studies ◽  
Liver And Kidney

1. Administration of a single dose of dimethylnitrosamine to rats temporarily fed on a protein-deficient diet causes a high incidence of kidney tumours. The effect of such a dose of dimethylnitrosamine (40mg/kg body wt.) on metabolism of nucleic acids and protein in rat liver and kidneys was examined during the week immediately after administration. 2. Incorporation of [14C]leucine and [14C]orotate into hepatic macromolecules was inhibited within 5h of injection of dimethylnitrosamine, and did not recover for at least 5 days. Interpretation of these results is complicated by the concomitant extensive hepatic necrosis. 3. Renal RNA synthesis was assayed by incorporation of [14C]orotate in vivo and measurement of DNA-dependent RNA polymerase activity in vitro. Both systems indicate biphasic inhibition; minimal activity was recorded 9h and 3 days after treatment. Changes in incorporation of [14C]leucine into renal protein were similar but less marked. 4. Sucrose-density-gradient analysis of renal cytoplasmic RNA indicated increased synthesis of rRNA 24h after injection of the nitrosamine. The rate of loss of radioactivity from kidney ribosomes pre-labelled with [14C]orotate was not modified by dimethylnitrosamine. 5. Dimethylnitrosamine increased incorporation of [3H]-thymidine into renal DNA. The three distinct periods of stimulated synthesis observed are discussed, with particular reference to recently published morphological studies of the sequential development of kidney tumours induced by dimethylnitrosamine in protein-depleted rats.

scholarly journals Phenylhydrazine-mediated induction of haem oxygenase activity in rat liver and kidney and development of hyperbilirubinaemia. Inhibition by zinc-protoporphyrin

1984 ◽  
Vol 217 (2) ◽  
pp. 409-417 ◽  
Author(s):  
M D Maines ◽  
J C Veltman
Keyword(s):  
Rat Liver ◽  
Zinc Protoporphyrin ◽  
Serum Total Bilirubin ◽  
Potent Inducer ◽  
Oxygenase Activity ◽  
Liver And Kidney ◽  
Haem Oxygenase ◽  
Cytochrome P 450

Phenylhydrazine was found to be a potent inducer of microsomal haem oxygenase activity in rat liver and kidney, but not in spleen. The phenylhydrazine-mediated increase in haem oxygenase activity was time-dependent. Maximum activity was attained 12h after treatment in the liver, and 24h after treatment in the kidney. The increases in the activity of haem oxygenase in the liver and the kidney could be inhibited by cycloheximide. Furthermore, the increases could not be elicited by the treatment of microsomal preparations in vitro with phenylhydrazine. In consonance with the increased haem oxygenase activity, a marked increase (16-fold) was observed in the serum total bilirubin concentration in phenylhydrazine-treated rats. The mechanism of haem degradation promoted by phenylhydrazine in vivo appears to differ from that in vitro; only in the former case is bilirubin formed as the end-product of haem degradation. When rats were given zinc-protoporphyrin (40 mumol/kg) 12h before and after phenylhydrazine treatment, the phenylhydrazine-mediated increases in haem oxygenase activity in the liver and the kidney were effectively blocked. Treatment of rats in vivo with the metalloporphyrin also inhibited the activity of splenic haem oxygenase, and promoted a major decrease in the serum bilirubin levels. In phenylhydrazine-treated animals, the microsomal content of cytochrome P-450 was significantly decreased in the absence of a decrease in the microsomal haem concentration. The decrease in cytochrome P-450 content was accompanied by an increased absorption in the 420nm region of the reduced CO-difference spectrum, suggesting the conversion of the cytochrome to an inactive form. The marked depletion of cellular glutathione levels suggests that this conversion may be related to the action of active intermediates and free radicals formed in the course of the interaction of phenylhydrazine with the haem moiety of cytochrome P-450.

scholarly journals Metabolism of a glutathione conjugate of 2-hydroxyoestradiol by rat liver and kidney preparations in vitro

1970 ◽  
Vol 116 (5) ◽  
pp. 913-917 ◽  
Author(s):  
John S. Elce
Keyword(s):  
Rat Liver ◽  
Microsomal Fraction ◽  
Male Rat ◽  
Amino Group ◽  
Glutathione Conjugate ◽  
Acetyl Coenzyme A ◽  
Adult Male Rat ◽  
Liver And Kidney

Adult male rat liver and kidney preparations were incubated with (2-hydroxyoestradiol-1-yl)[35S]glutathione. The glutamic acid and glycine residues were removed by enzymes present in the kidney microsomal fraction; the liver preparations had no effect. The resulting 2-hydroxyoestradiol–cysteine conjugate was acetylated at the α-amino group by both liver and kidney homogenates fortified with acetyl-coenzyme A, but not significantly in the absence of this coenzyme, or by liver or kidney slices. These results suggest that an oestrogen–glutathione conjugate, if formed in vivo, would be converted into the corresponding mercapturic acid before excretion.

scholarly journals Effect of different thyroid states on rat liver glucokinase synthesis and degradation in vivo.

1981 ◽  
Vol 256 (18) ◽  
pp. 9490-9494
Author(s):  
W. Sibrowski ◽  
M.J. Müller ◽  
H.J. Seitz
Keyword(s):  
Rat Liver ◽  
Synthesis And Degradation
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