Phenylarsine oxide inhibition of endocytosis: effects on asialofetuin internalization

1989 ◽  
Vol 257 (2) ◽  
pp. C182-C184 ◽  
Author(s):  
A. E. Gibson ◽  
R. J. Noel ◽  
J. T. Herlihy ◽  
W. F. Ward
Keyword(s):  
Oxygen Consumption ◽  
Rat Hepatocytes ◽  
Atp Content ◽  
Phenylarsine Oxide ◽  
Careful Evaluation ◽  
Isolated Rat Hepatocytes ◽  
Energy Stores ◽  
Experimental Preparation ◽  
Oxide Inhibition ◽  
Slight Inhibition

The aim of this work was to establish to what extent the concentrations over which phenylarsine oxide (PAO) inhibits oxygen consumption and decreases cellular ATP content overlap with those used to inhibit protein internalization. The effects of PAO (1-100 microM) on 125I-labeled asialofetuin internalization, oxygen consumption, ATP content, and lactate dehydrogenase (LDH) latency of isolated rat hepatocytes were determined. Ten micromoles/liter PAO blocked 125I-asialofetuin internalization but had no effect on ATP content up to 20 min, only a slight inhibition (18%) on oxygen consumption, and no effect on LDH latency. Higher concentrations of PAO had increasingly deleterious effects on the parameters. These results show that higher concentrations of PAO severely affect the energy stores as well as integrity of the hepatocyte. We concluded that 1) use of PAO requires careful evaluation of its effects in each experimental preparation and 2) it should be possible to establish time and concentration parameters for use of PAO as an inhibitor of endocytosis while minimizing the influence of its other cellular actions.

scholarly journals Interactions of dietary fat and 2,5-anhydro-d-mannitol on energy metabolism in isolated rat hepatocytes

2002 ◽  
Vol 282 (3) ◽  
pp. R715-R720 ◽  
Author(s):  
Hong Ji ◽  
Grazyna Graczyk-Milbrandt ◽  
Mary D. Osbakken ◽  
Mark I. Friedman
Keyword(s):  
Oxygen Consumption ◽  
Rat Hepatocytes ◽  
Isolated Hepatocytes ◽  
Metabolic Effects ◽  
Atp Content ◽  
Isolated Rat Hepatocytes ◽  
Palmitate Oxidation ◽  
Low Carbohydrate ◽  
Lower Oxygen ◽  
Hepatocyte Metabolism

The fructose analog 2,5-anhydro-d-mannitol (2,5-AM) stimulates feeding in rats by reducing ATP content in the liver. These behavioral and metabolic effects occur with rats fed a high-carbohydrate/low-fat (HC/LF) diet, but they are prevented or attenuated when the animals eat high-fat/low-carbohydrate (HF/LC) food. To examine the metabolic bases for this effect of diet, we assessed the actions of 2,5-AM on ATP content, oxygen consumption, and substrate oxidation in isolated hepatocytes from rats fed one of the two diets. Compared with cells from rats fed the HC/LF diet (“HC/LF” cells), cells from rats fed the HF/LC diet (“HF/LC” cells) had similar ATP contents but lower oxygen consumption, decreased fructose, and increased palmitate oxidation. 2,5-AM did not decrease ATP content or oxygen consumption in HF/LC cells as much as it did in HC/LF hepatocytes, and it only affected fructose and palmitate oxidation in HC/LF cells.31P-NMR spectroscopy indicated that differences in phosphate trapping accounted for differences in depletion of ATP by 2,5-AM. These results suggest that intake of the HF/LC diet prevents the eating response and attenuates the decline in liver ATP by shifting hepatocyte metabolism to favor fat over carbohydrate as an energy-yielding substrate.

Different relationships between cellular ATP and hepatic uptake among taurocholate, cholate, and organic anions

1993 ◽  
Vol 264 (4) ◽  
pp. G693-G701 ◽  
Author(s):  
M. Yamazaki ◽  
H. Suzuki ◽  
M. Hanano ◽  
Y. Sugiyama
Keyword(s):  
Initial Velocity ◽  
Organic Anion ◽  
Rat Hepatocytes ◽  
Inhibitory Effect ◽  
Organic Anions ◽  
Metabolic Inhibitors ◽  
Atp Content ◽  
Isolated Rat Hepatocytes ◽  
Total Uptake ◽  
Ca Uptake

Effects of cellular ATP content on uptake of cholate (CA) and organic anions (OAs; dibromosulfophthalein and benzylpenicillin) by isolated rat hepatocytes were investigated and were compared with that on taurocholate (TCA). Within 5 min of exposure to metabolic inhibitors (MIs), cellular ATP content fell to less than one-fifth of the control value, and the initial velocity of the total uptake of CA, Na(+)-independent uptake of CA and TCA, and the uptake of the OAs dropped in parallel with the decrease in cellular ATP. Whereas for the total uptake of TCA, the initial uptake remained virtually unchanged for a 5-min incubation with the MIs; a significant decrease in uptake was observed only after longer incubation times. Under variously ATP-decreased conditions, the initial velocity of the total uptake of CA and OAs was demonstrated to have a saturable relation to cellular ATP content, irrespective of exposure time to MIs. A difference in the Na(+)-dependent uptake of TCA and CA was also observed in terms of the inhibitory effect of the organic anion pravastatin. That is, the inhibition by pravastatin was partial for TCA uptake but almost complete for CA uptake. These findings suggest the following. 1) The mechanism of Na(+)-dependent CA uptake is different from that of TCA. 2) The Na(+)-independent uptake of bile acids and organic anions may be driven either by ATP hydrolysis (primary active transport) or by an as yet unidentified ion gradient that dissipates more rapidly than the Na+ gradient.

scholarly journals Differential arrest of secretory protein transport in cultured rat hepatocytes by azide treatment.

1988 ◽  
Vol 107 (6) ◽  
pp. 2503-2510 ◽  
Author(s):  
R Persson ◽  
E Ahlström ◽  
E Fries
Keyword(s):  
Intracellular Transport ◽  
Protein Transport ◽  
Rat Hepatocytes ◽  
Secretory Protein ◽  
Secretory Proteins ◽  
Atp Content ◽  
Isolated Rat Hepatocytes ◽  
Atp Level ◽  
Atp Levels ◽  
Endoglycosidase H

The effect of reduced cellular ATP content on intracellular transport of two secretory proteins, albumin and haptoglobin, in isolated rat hepatocytes was studied. The cells were labeled with [35S]methionine and the cellular ATP content was then rapidly reduced to different stable levels by incubation with azide at different concentrations (2.0-10 mM). The amount of the radioactively labeled secretory proteins in the cells and in the medium after 150 min of incubation was determined by immunoprecipitation followed by gel electrophoresis, fluorography, and densitometry. At progressively lower ATP levels, down to 50% of normal, the protein secretion was unaffected, whereas at even lower levels an increasing portion of the proteins remained in the cells; at 30 and 10% of normal ATP level, 25 and 75% of albumin, respectively, was arrested intracellularly. Analysis of the carbohydrate structure of intracellularly arrested haptoglobin showed that in cells with an ATP level of approximately 30% of normal, the majority of haptoglobin molecules (55%) were fully or partially resistant to endoglycosidase H. This result indicates that exit from the medial and/or the trans part of the Golgi complex (GC) was inhibited under these conditions. It also shows that the protein had accumulated in the GC, since under normal conditions the fraction of the intracellular haptoglobin that is endoglycosidase H resistant is approximately 10%. By similar criteria it was found that at ATP levels below 10% of normal transport of haptoglobin from the endoplasmic reticulum to the medial GC (and possibly also to the cis GC) as well as from the trans GC to the medium were blocked.

ATP-dependent efflux of GSSG and GS-conjugate from isolated rat hepatocytes

1990 ◽  
Vol 258 (5) ◽  
pp. G699-G706 ◽  
Author(s):  
R. P. Oude Elferink ◽  
R. Ottenhoff ◽  
W. G. Liefting ◽  
B. Schoemaker ◽  
A. K. Groen ◽  
...  
Keyword(s):  
Transport System ◽  
Rat Hepatocytes ◽  
Cell Types ◽  
Oxidized Glutathione ◽  
Atp Content ◽  
Efflux Rate ◽  
Isolated Rat Hepatocytes ◽  
Transport Defect ◽  
Dependent Transport ◽  
Isolated Rat

The driving force for efflux of dinitrophenyl-glutathione (GS-DNP) and oxidized glutathione (GSSG) from freshly isolated rat hepatocytes was studied. Incubation of hepatocytes in Krebs with increasing K+ concentrations (equivalently replaced for Na+) or in Krebs with 3 mM ouabain led to a partial or complete dissipation of the plasma membrane potential, as measured by the equilibrium distribution of 36Cl-. This had no effect on the initial efflux rate of GSSG and GS-DNP. On the other hand, partial depletion of the cellular ATP content via different independent mechanisms significantly reduced the initial efflux rate of these compounds. Titration of the cellular ATP content by incubation of the cells with different concentrations of atractyloside revealed a linear relation between the cellular ATP content and the initial efflux rate of GS-DNP. The efflux of GS-DNP was also studied in hepatocytes from mutant rats with hepatobiliary transport defect (TR- rats). These rats have a hereditary canalicular secretion defect for a number of organic anions including GS-DNP. As we have shown previously, the efflux of GS-DNP from TR- rat hepatocytes is significantly slower than from normal hepatocytes (J. Clin. Invest. 84: 476-483, 1989). Depletion of the cellular ATP content in these cells had no significant effect on the residual efflux of GS-DNP. From these studies, we conclude that an ATP-dependent transport system for oxidized glutathione and glutathione conjugates is involved in the biliary transport of these compounds. The possible relation of this transport system with that described in other cell types and tissues, like erythrocytes and heart sarcolemma, is discussed.

scholarly journals Lysosomal triacylglycerol lipase and lipolysis in isolated rat hepatocytes.

1979 ◽  
Vol 254 (18) ◽  
pp. 8841-8846
Author(s):  
L.J. Debeer ◽  
J. Thomas ◽  
P.J. De Schepper ◽  
G.P. Mannaerts
Keyword(s):  
Rat Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Triacylglycerol Lipase ◽  
Isolated Rat
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