scholarly journals Mitochondrial and cytosolic ATP/ADP ratios in rat liver in vivo

1981 ◽  
Vol 200 (2) ◽  
pp. 405-408 ◽  
Author(s):  
W D Schwenke ◽  
S Soboll ◽  
H J Seitz ◽  
H Sies
Keyword(s):  
Rat Liver ◽  
Oxygen Supply ◽  
Isolated Hepatocytes ◽  
Perfused Liver ◽  
Mitochondrial Matrix ◽  
Atp Content ◽  
Anaesthetized Rats

The ratio of ATP content/ADP content in livers from unanaesthetized fed rat was 0.9 in the mitochondrial matrix and 6.9 in the cytosol; the values for starved (48 h) animals were 1.0 and 5.9 respectively. The mitochondrial ratios observed in unanaesthetized animals were higher than in haemoglobin-free-perfused liver and lower than in isolated hepatocytes. Possible reasons for these differences may be related to oxygen supply and/or other factors. Further, data from anaesthetized rats with the liver exposed are given: mitochondrial ATP/ADP ratios were decreased with pentobarbital, but less so with ketamine as narcotic agent.

scholarly journals Mitochondrial and cytosolic ATP/ADP ratios in isolated hepatocytes. A comparison of the digitonin method and the non-aqueous fractionation procedure

1980 ◽  
Vol 192 (3) ◽  
pp. 951-954 ◽  
Author(s):  
S Soboll ◽  
T P M Akerboom ◽  
W D Schwenke ◽  
R Haase ◽  
H Sies
Keyword(s):  
Isolated Hepatocytes ◽  
Perfused Liver ◽  
Mitochondrial Matrix ◽  
Atp Content ◽  
Isolated Cells ◽  
Fractionation Procedure ◽  
Biochemical Difference ◽  
Methodological Artifact

The ratio of ATP content/ADP content in the mitochondrial matrix was found to be 2.07 +/- 0.21 and 2.26 +/- 0.22 as determined with six different preparations of isolated hepatocytes subfractionated with the digitonin and non-aqueous-fractionation procedures, respectively. In contrast, the mitochondrial matrix ATP/ADP determined with isolated haemoglobin-free perfused liver by using the non-aqueous-fractionation procedure was about 0.2, whereas the cytosolic values obtained with isolated cells and with the intact organ were similar. It is concluded that the relatively higher ATP/ADP ratio in the mitochondrial matrix of isolated hepatocytes represents a biochemical difference due to properties of the model rather than a methodological artifact.

scholarly journals Polyribosomes in isolated liver cells. Preparative procedures, effects of incubation and correlation with protein synthesis

1980 ◽  
Vol 186 (1) ◽  
pp. 35-45 ◽  
Author(s):  
A J Dickson ◽  
C I Pogson
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Isolated Hepatocytes ◽  
Liver Cells ◽  
Liver Protein ◽  
Isolated Cells ◽  
Isolated Liver Cells ◽  
Rat Liver Cells ◽  
Isolated Liver

Methods have been derived which permit the isolation of undergraded polyribosomes from isolated rat liver cells. Under the conditions used the polyribosome profile of hepatocytes immediately after isolation was essentially identical with that from intact liver. However, during incubation of cells in complex physiological media there was a progressive dissociation of polyribosomes. The addition of a variety of factors that produce reaggregation of polyribosomes in rat liver in vivo did not prevent dissociation during cell incubations. Although large polyribosomes were lost most rapidly, the albumin-synthesizing capacity of isolated cells was not selectively lost when compared with total protein synthesis. The significance of these results for the use of isolated hepatocytes in the study of liver protein synthesis is discussed.

scholarly journals NH4+ metabolism and the intracellular pH in isolated perfused rat liver

1993 ◽  
Vol 293 (3) ◽  
pp. 667-673 ◽  
Author(s):  
J Zange ◽  
J Gronczewski ◽  
A W H Jans
Keyword(s):  
Intracellular Ph ◽  
Rat Liver ◽  
Isolated Hepatocytes ◽  
Isolated Perfused Rat Liver ◽  
Small Range ◽  
Perfused Rat Liver ◽  
Atp Content ◽  
Intracellular Acidification ◽  
Subsequent Conversion ◽  
Intracellular Alkalinization

The effects of NH4+ on the intracellular pH (pHi) and on the ATP content in isolated perfused rat liver were studied by 31P n.m.r. spectroscopy. In the initial phase of perfusion an average pHi of 7.29 +/- 0.04 was estimated. The presence of low (0.5 mmol/l) and high (10 mmol/l) doses of NH4Cl induced significant intracellular acidification by -0.06 +/- 0.03 and -0.11 +/- 0.03 pH unit respectively. This effect was in contrast with the transient intracellular alkalinization observed in preliminary studies on isolated hepatocytes, which was caused by a passive entry of NH3 by non-ionic diffusion and subsequent conversion into NH4+. During application of 0.5 mmol/l NH4Cl the liver released 0.54 +/- 0.06 mumol of urea/min per g into the perfusate. When the intracellular availability of HCO3- was decreased by acetazolamide (0.5 mmol/l) or by removal of HCO3- from the perfusion medium, the decrease in pHi by NH4Cl application was significantly lower than under control conditions. Furthermore, synthesis of urea was significantly inhibited by the decrease in intracellular HCO3-. Under these conditions, 10 mmol/l NH4Cl caused the transient alkalinization that was expected because of the passive uptake of uncharged NH3. Therefore, it is concluded that the intracellular acidification induced by NH4Cl is caused by the continuous utilization of intracellular HCO3- via the synthesis of urea. This metabolic effect on pHi dominates the effects of passive NH3 entry. The rate of urea formation depends on continuous efflux of H+, which is strictly limiting the degree of intracellular acidification within a small range. If the extrusion of H+ by the Na+/H+ exchanger was inhibited by amiloride (0.5 mmol/l) during the NH4Cl application, the decrease in pHi was amplified and the formation of urea was significantly inhibited. The application of NH4Cl at 0.5 or 10 mmol/l decreased the ATP content by 11% or 22% respectively.

scholarly journals Glutathione analogues as novel inhibitors of rat and human glutathione S-transferase isoenzymes, as well as of glutathione conjugation in isolated rat hepatocytes and in the rat in vivo

1995 ◽  
Vol 308 (1) ◽  
pp. 283-290 ◽  
Author(s):  
S Ouwerkerk-Mahadevan ◽  
J H van Boom ◽  
M C Dreef-Tromp ◽  
J H T M Ploemen ◽  
D J Meyer ◽  
...  
Keyword(s):  
Ethyl Ester ◽  
Rat Liver ◽  
Rat Hepatocytes ◽  
Isolated Hepatocytes ◽  
Glutathione S Transferase ◽  
Isolated Rat Hepatocytes ◽  
Glutathione S Transferases ◽  
Gamma S ◽  
Isolated Rat

Inhibitors of rat and human Alpha- and Mu-class glutathione S-transferases that effectively inhibit the glutathione (GSH) conjugation of bromosulphophthalein in the rat liver cytosolic fraction, isolated rat hepatocytes and in the rat liver in vivo have been developed. The GSH analogue (R)-5-carboxy-2-gamma-(S)-glutamylamino-N-hexylpentamide [Adang, Brussee, van der Gen and Mulder (1991) J. Biol. Chem. 266, 830-836] was used as the lead compound. To obtain more potent inhibitors, it was modified by replacement of the N-hexyl moiety by N-2-heptyl and by esterification of the 5-carboxy group with ethyl and dodecyl groups. In isolated hepatocytes, the branched N-2-heptyl derivatives were stronger inhibitors of GSH conjugation of bromosulphophthalein than the N-hexyl derivatives. The ethyl ester compounds were more efficient than the corresponding unesterified derivatives. The dodecyl ester of the N-2-heptyl analogue was the most effective inhibitor in isolated hepatocytes, but was relatively toxic in vivo. However, the corresponding ethyl ester was a potent in vivo inhibitor: GSH conjugation of bromosulphophthalein (as assessed by biliary excretion of the conjugate) was decreased by 70% after administration of a dose of 200 mumol/kg. The isoenzyme specificity of the inhibitors towards purified rat and human glutathione S-transferases was also examined. The unesterified compounds were more potent than the esterified analogues, and inhibited Alpha- and Mu-class isoenzymes of both rat and human glutathione S-transferase (Ki range 1-40 microM). Other GSH-dependent enzymes, i.e. GSH peroxidase, GSH reductase and gamma-glutamyltranspeptide, were not inhibited. Thus (R)-5-ethyloxycarbonyl-2-gamma-(S)-glutamylamino-N-2-hept ylpentamide, the in vivo inhibitor of GSH conjugation, may be useful in helping to assess the role of the Alpha and Mu classes of glutathione S-transferases in cellular biochemistry, physiology and pathology.

Repression of protein synthesis and mTOR signaling in rat liver mediated by the AMPK activator aminoimidazole carboxamide ribonucleoside

2005 ◽  
Vol 288 (5) ◽  
pp. E980-E988 ◽  
Author(s):  
Ali K. Reiter ◽  
Douglas R. Bolster ◽  
Stephen J. Crozier ◽  
Scot R. Kimball ◽  
Leonard S. Jefferson
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Translational Control ◽  
Serum Insulin ◽  
Experimental Models ◽  
Mtor Signaling ◽  
Initiation Factor ◽  
Perfused Liver

The studies described herein were designed to investigate the effects of 5-aminoimidazole-4-carboxamide-1-β-d-ribonucleoside (AICAR), an activator of the AMP-activated protein kinase (AMPK), on the translational control of protein synthesis and signaling through the mammalian target of rapamycin (mTOR) in rat liver. Effects of AICAR observed in vivo were compared with those obtained in an in situ perfused liver preparation to investigate activation of AMPK in the absence of accompanying changes in hormones and nutrients. AMPK became hyperphosphorylated, as assessed by a gel-shift analysis, in response to AICAR both in vivo and in situ; however, increased relative phosphorylation at the Thr172 site on the kinase was observed only in perfused liver. Phosphorylation of AMPK either in vivo or in situ was associated with a repression of protein synthesis as well as decreased phosphorylation of a number of targets of mTOR signaling including ribosomal protein S6 kinase 1, eukaryotic initiation factor (eIF)4G, and eIF4E-binding protein (4E-BP)1. The phosphorylation changes in eIF4G and 4E-BP1 were accompanied by a reduction in the amount of eIF4E present in the active eIF4E·eIF4G complex and an increase in the amount present in the inactive eIF4E·4E-BP1 complex. Reduced insulin signaling as well as differences in nutrient availability may have contributed to the effects observed in vivo as AICAR caused a fall in the serum insulin concentration. Overall, however, the results from both experimental models support a scenario in which AICAR directly represses protein synthesis and mTOR signaling in the liver through an AMPK-dependent mechanism.

scholarly journals Rapid thyroid-hormone effect on mitochondrial and cytosolic ATP/ADP ratios in the intact liver cell

1985 ◽  
Vol 227 (1) ◽  
pp. 149-153 ◽  
Author(s):  
H J Seitz ◽  
M J Müller ◽  
S Soboll
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Adenine Nucleotide ◽  
Perfused Liver ◽  
Mitochondrial Matrix ◽  
Isolated Mitochondria ◽  
Hormone Effect ◽  
Adenine Nucleotide Transport ◽  
Atp Regeneration

The effect of thyroid-hormone application on cytosolic and mitochondrial ATP/ADP ratio was investigated in rat liver in vivo and in the isolated perfused organ. In vivo the ATP/ADP ratio in livers from hypothyroid rats was 0.84 +/- 0.08 in the mitochondrial matrix and 5.6 +/- 0.9 in the cytosol, as was observed in euthyroid controls. In contrast, hyperthyroidism was followed by a significant decrease in the mitochondrial and by an increase in the cytosolic ATP/ADP ratio (to 0.34 +/- 0.06 and 11.3 +/- 2.8 respectively). In the perfused liver from hypothyroid animals, addition of L-3,3',5-tri-iodothyronine in the perfusate also provoked, within 2 h, a significant decrease in the mitochondrial ATP/ADP ratio, whereas the cytosolic ratio was unaffected. From these and previous data in the isolated perfused liver and in isolated mitochondria from hypothyroid and tri-iodothyronine-treated rats it is concluded that thyroid hormones increase mitochondrial respiration and ATP regeneration, which is associated with an acceleration of mitochondrial adenine nucleotide transport and significant alterations in the mitochondrial and cytosolic ATP/ADP ratios.

Aromatic hydroxylation of amphetamine with rat liver microsomes, perfused liver, and isolated hepatocytes

1978 ◽  
Vol 27 (21) ◽  
pp. 2525-2529 ◽  
Author(s):  
Ruth E. Billings ◽  
Patrick J. Murphy ◽  
Robert E. McMahon ◽  
James Ashmore
Keyword(s):  
Rat Liver ◽  
Liver Microsomes ◽  
Isolated Hepatocytes ◽  
Rat Liver Microsomes ◽  
Perfused Liver ◽  
Aromatic Hydroxylation
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