scholarly journals The mechanism of hepatic iron uptake from native and denatured transferrin and its subcellular metabolism in the liver cell

1979 ◽  
Vol 182 (1) ◽  
pp. 117-125 ◽  
Author(s):  
J P Milsom ◽  
R G Batey
Keyword(s):  
Rat Liver ◽  
Liver Cell ◽  
Iron Uptake ◽  
Subcellular Fractionation ◽  
Hepatic Iron ◽  
Lysosomal Fraction ◽  
Uptake Process ◽  
Liver Homogenates ◽  
Uptake And Metabolism

Hepatic iron uptake and metabolism were studied by subcellular fractionation of rat liver homogenates after injection of rats with a purified preparation of either native or denatured rat transferrin labelled with 125I and 59Fe. (1) With native transferrin, hepatic 125I content was maximal 5 min after injection and then fell. Hepatic 59Fe content reached maximum by 16 h after injection and remained constant for 14 days. Neither label appeared in the mitochondrial or lysosomal fractions. 59Fe appeared first in the supernatant and, with time, was detectable as ferritin in fractions sedimented with increasingly lower g forces. (2) With denatured transferrin, hepatic content of both 125I and 59Fe reached maximum by 30 min. Both appeared initially in the lysosomal fraction. With time, they passed into the supernatant and 59Fe became incorporated into ferritin. The study suggests that hepatic iron uptake from native transferrin does not involve endocytosis. However, endocytosis of denatured transferrin does occur. After the uptake process, iron is gradually incorporated into ferritin molecules, which subsequently polymerize; there is no incorporation into other structures over 14 days.

Uptake and distribution of transferrin and iron in perfused, iron-deficient rat liver

1989 ◽  
Vol 256 (6) ◽  
pp. G1022-G1027
Author(s):  
J. M. Holmes ◽  
E. H. Morgan
Keyword(s):  
Iron Deficiency ◽  
Rat Liver ◽  
Iron Uptake ◽  
Subcellular Fractionation ◽  
Rat Serum ◽  
Iron Deficient ◽  
Uptake Process ◽  
Transferrin Uptake ◽  
Rat Serum Albumin

Uptake of transferrin and iron by the rat liver was investigated by perfusion in vitro with 125I-59Fe-labeled rat transferrin and subcellular fractionation on sucrose density gradients. Most of the 125I-transferrin was located in a low-density vesicle fraction. The 59Fe was in three peaks, of lower, the same, and higher densities than the transferrin peak. Iron deficiency resulted in a large increase in transferrin and iron uptake into all subcellular fractions. When livers were perfused with increasing concentrations of transferrin the uptake into the different peaks of transferrin and iron increased in a curvilinear fashion, which indicated that uptake occurred by saturable and nonsaturable processes, both of which increased in iron deficiency. In contrast, the uptake of 131I-labeled rat serum albumin increased linearly with concentration, and there was no difference between control and iron-deficient livers. It is concluded that iron deficiency leads to an increase in the number of high-affinity transferrin receptors and receptor-mediated endocytosis of transferrin. It also increases a nonsaturable transferrin uptake process that is probably due to adsorptive, but selective, endocytosis of transferrin.

LIVER DISTRIBUTION OF COPPER AND 99Mo IN SHEEP FOLLOWING INTRAVENOUS ADMINISTRATION OF COPPER SULFATE AND [99Mo]-TETRATHIOMOLYBDATE

1986 ◽  
Vol 66 (2) ◽  
pp. 563-565
Author(s):  
C. A. KELLKHER ◽  
M. IVAN
Keyword(s):  
Key Words ◽  
Copper Sulfate ◽  
Intravenous Administration ◽  
Subcellular Distribution ◽  
Subcellular Fractionation ◽  
Intravenous Dose ◽  
Single Intravenous Dose ◽  
Lysosomal Fraction ◽  
Liver Homogenates

The effect of a single intravenous dose of 0, 50 or 100 g molybdenum (Mo) as [99Mo] labelled sodium tetrathiomolybdate (Na2MoS4) on the subcellular distribution of copper (Cu) in the liver was studied in three groups of four sheep. The sheep received a 35-mg intravenous dose of Cu 20 h prior, and were killed 24 h after the dosing with Mo. Subcellular fractionation of liver homogenates revealed that [Formula: see text] may react with Cu in the nuclear (lysosomal) fraction. Key words: Sheep, copper, molybdenum, tetrathiomolybdate, liver fractions

Deacylation of bis(monoacylglycero)phosphate by lysosomal and microsomal lysophospholipases from rat liver

1982 ◽  
Vol 60 (6) ◽  
pp. 599-607 ◽  
Author(s):  
Srebrenka Huterer ◽  
John R. Wherrett
Keyword(s):  
Arachidonic Acid ◽  
Rat Liver ◽  
Ethylenediaminetetraacetic Acid ◽  
Subcellular Fractionation ◽  
Alkaline Ph ◽  
Phosphodiesterase Activity ◽  
Triton Wr 1339 ◽  
Liver Homogenates ◽  
Triton X ◽  
Catalytic Exchange

The degradation of bis(monoacylglycero)phosphate by subcellular fractions of rat liver, using substrates labelled biosynthetically with [14C]arachidonic acid and [4C]oleic acid and chemically by catalytic exchange with tritium, was studied. Liver homogenates catalyzed maximum degradation at alkaline pH and subcellular fractionation localized this activity to microsomes. The degradation by microsomes was found to be a deacylation to lysophosphatidylglycerol and was without phosphodiesterase activity. The deacylation was maximal at pH 8.3 and did not require Ca2+ or Mg2+ but was stimulated by ethylenediaminetetraacetic acid and inhibited by Fe2+ and Hg2+. It was also inhibited by p-chloromercuribenzoate, deoxycholate, Triton X-100, and Triton WR-1339. The apparent Km was determined to be 5.5 × 10−5 M and the corresponding Vmax was 4.1 nmol product released/min per milligram protein. The three labelled substrates were degraded by microsomes to give the same products in similar relative proportions. Degradation of bis(monoacylglycero)phosphate by lysosomes was maximal at acid pH as previously described by Y. Matsuzawa and K. Y. Hosteller. Contrary to their finding, deacylase activity in lysosomes was much greater than phosphodiesterase activity. The lysosomal deacylase but not the phosphodiesterase activity was inhibited reversibly by n-butanol. Sphingomyelin inhibited the microsomal deacylase but not the lysosomal deacylase.

scholarly journals The uptake and metabolism of chylomicron-remnant lipids by rat liver parenchymal and non-parenchymal cells in vitro

1985 ◽  
Vol 232 (2) ◽  
pp. 395-401 ◽  
Author(s):  
P M Lippiello ◽  
P J Sisson ◽  
M Waite
Keyword(s):  
Endothelial Cells ◽  
Rat Liver ◽  
Kupffer Cells ◽  
Liver Cell ◽  
Cholesterol Ester ◽  
Cell Types ◽  
Chylomicron Remnant ◽  
Parenchymal Cells ◽  
Uptake And Metabolism

The uptake and metabolism of chylomicron-remnant lipids by individual liver cell types was examined by incubating remnants with monolayer cultures of hepatocytes, Kupffer cells, and endothelial cells from rat liver. Remnants were prepared in vitro from radiolabelled mesenteric-lymph chylomicra, utilizing either purified lipoprotein lipase from bovine milk, or plasma isolated from heparinized rats. The resulting particles contained [3H]phosphatidylcholine and cholesterol, and [14C]oleate in the acylglycerol, phospholipid, fatty-acid and cholesterol-ester fractions. The capacities of the three cell types for uptake of both [3H]lipids and [14C]lipids were determined to be, on a per-cell basis, in the order: Kupffer greater than hepatocytes greater than endothelial. The relative proportions of [3H]phospholipid and total [3H]cholesterol taken up by hepatocytes and non-parenchymal cells remained constant with time. The uptake of [14C]oleoyl lipids by all three cell types was slightly greater than that of the total [3H]cholesterol and [3H]phospholipid components. There was evidence of cholesterol-ester hydrolysis and turnover of [14C]oleate in the phospholipid fraction in hepatocytes and Kupffer cells, but not endothelial cells, over the first 2 h. With both remnant preparations, these observations indicate that significant differences exist between the three major liver cell types with respect to the uptake and metabolism of remnant lipid components.

scholarly journals Effect of chloramphenicol on ribonucleic acid synthesis in liver cells in suspension

1965 ◽  
Vol 97 (1) ◽  
pp. 67-73 ◽  
Author(s):  
ST Jacob ◽  
PM Bhargava
Keyword(s):  
Rat Liver ◽  
Liver Cell ◽  
Ribonucleic Acid ◽  
Acid Synthesis ◽  
Inhibitory Effect ◽  
Cell Suspensions ◽  
Perfused Rat Liver ◽  
Tissue Slices ◽  
Hepatic Cells ◽  
Liver Homogenates

1. Chloramphenicol has a stimulatory effect on the incorporation of radioactive phosphate into the RNA of perfused rat-liver slices, whole liver homogenates or the liver-cell suspensions, and no effect on the incorporation of [(14)C]adenine and [(14)C]uracil into the RNA of the tissue slices. 2. Chloramphenicol completely inhibits the incorporation of labelled adenine and uracil into the RNA of the cell suspensions, or into the RNA of homogenates derived from the whole liver tissues. 3. Chloramphenicol has at most a slight inhibitory effect on the transport of labelled adenine or uracil in the hepatic cells in suspension; in the slices, the transport of these bases is not inhibited at all. 4. The above observations indicate that: (a) unlike the tissue slices, hepatic cells in suspension are permeable to chloramphenicol; (b) in the presence of chloramphenicol, for reasons that are not clear, the conversion of the base into the appropriate nucleotide does not proceed.

scholarly journals Multiphoton spectral analysis of benzo[a]pyrene uptake and metabolism in a rat liver cell line

2011 ◽  
Vol 253 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Rola Barhoumi ◽  
Youssef Mouneimne ◽  
Ernesto Ramos ◽  
Christophe Morisseau ◽  
Bruce D. Hammock ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Cell Line ◽  
Rat Liver ◽  
Liver Cell ◽  
Liver Cell Line ◽  
Uptake And Metabolism

scholarly journals Subcellular localization of a rat liver enzyme converting thyroxine into tri-iodothyronine and possible involvement of essential thiol groups

1976 ◽  
Vol 157 (2) ◽  
pp. 479-482 ◽  
Author(s):  
T J Visser ◽  
I Does-Tobé ◽  
R Docter ◽  
G Hennemann
Keyword(s):  
Rat Liver ◽  
Essential Role ◽  
Microsomal Fraction ◽  
Thiol Group ◽  
Subcellular Fractionation ◽  
Enzymic Activity ◽  
Marker Enzyme ◽  
Converting Enzyme ◽  
Thiol Groups ◽  
Liver Homogenates

Experiments with rat liver homogenates showed that on subcellular fractionation the ability to catalyse the conversion of thyroxine into tri-iodothyronine was lost. The activity could in part be restored by addition of the cytosol to the microsomal fraction. Both components were found to be heat labile. The necessity of the presence of cytosol could be circumvented by incorporation of thiol-group-containing compounds in the medium. Optimal enzymic activity was observed in the presence of dithiothreitol and EDTA in medium of low osmolarity. By comparing the distribution of the converting enzyme over the subcellular fractions with a microsomal marker enzyme, glucose 6-phosphatase, it was demonstrated that the former is indeed of microsomal origin. Finally, it was shown that thiol groups play an essential role in the conversion of thyroxine into tri-iodothyronine.

Effects of Hypophysectomy on the Fine Structure of Rat Liver Cells

1967 ◽  
Vol 25 ◽  
pp. 156-157
Author(s):  
Robert R. Cardell
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Rat Liver ◽  
Liver Cell ◽  
Anterior Pituitary ◽  
Liver Cells ◽  
Biochemical Studies ◽  
Liver Functions ◽  
Rat Liver Cells ◽  
And Control

Hypophysectomy of the rat renders this animal deficient in the hormones of the anterior pituitary gland, thus causing many primary and secondary hormonal effects on basic liver functions. Biochemical studies of these alterations in the rat liver cell are quite extensive; however, relatively few morphological observations on such cells have been recorded. Because the available biochemical information was derived mostly from disrupted and fractionated liver cells, it seemed desirable to examine the problem with the techniques of electron microscopy in order to see what changes are apparent in the intact liver cell after hypophysectomy. Accordingly, liver cells from rats which had been hypophysectomized 5-120 days before sacrifice were studied. Sham-operated rats served as controls and both hypophysectomized and control rats were fasted 15 hours before sacrifice.

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