scholarly journals Endogenous hydroperoxide formation, cell volume and cellular K+ balance in perfused rat liver

1993 ◽  
Vol 296 (3) ◽  
pp. 701-707 ◽  
Author(s):  
N Saha ◽  
R Schreiber ◽  
S vom Dahl ◽  
F Lang ◽  
W Gerok ◽  
...  
Keyword(s):  
Monoamine Oxidase ◽  
Rat Liver ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Liver Mass ◽  
Hydroperoxide Formation ◽  
Close Relationship ◽  
H2o2 Formation ◽  
Net Release ◽  
K Release

Addition of benzylamine (0.5 mM) to isolated perfused rat liver led to a net release of K+ of 10.5 +/- 0.3 mumol/g, which was accompanied by a decrease in liver mass by 9.3 +/- 0.4% and a decrease of the intracellular water space by 13.7 +/- 0.6%, suggestive of hepatocellular shrinkage. Benzylamine had no effect on the perfusion pressure, and there was a close relationship between benzylamine-induced net K+ release and the accompanying decrease in liver mass. Benzylamine-induced net K+ release was sensitive to inhibition of monoamine oxidase by pargyline and increased with benzylamine flux through monoamine oxidase, suggesting its dependence on intracellular H2O2 formation. In line with this, infusion of H2O2 (but not of benzaldehyde, the other product of benzylamine metabolism) stimulated net K+ release from the liver. However, at a given H2O2 load K+ release was about 2-3-fold higher when H2O2 was generated intracellularly during the oxidation of benzylamine, as compared with exogenously delivered H2O2. Inhibition of catalase by 3-amino-1,2,4-triazole (0.2 mM) significantly increased the benzylamine-induced net K+ release as well as the benzylamine-induced release of GSSG into bile, but had no effect on benzylamine oxidation at monoamine oxidase. In the presence of Ba2+ (1 mM) or in Ca(2+)-free perfusions, the benzylamine-induced net K+ efflux was diminished by 60-70% or about 30%, respectively. This was not explained by the 20-30% decrease in flux through monoamine oxidase observed under these conditions. The results suggest that metabolic generation of H2O2 inside the liver leads to a net K+ efflux and subsequent hepatocellular shrinkage. Net K+ efflux under these conditions is enhanced when catalase is inhibited, suggesting that the rate of both intracellular H2O2 generation and degradation can modulate cellular K+ balance and cellular volume. The data support the idea that oxidative stress may affect hepatocellular functions also by lowering the hepatocellular hydration state.

scholarly journals Cell swelling increases bile flow and taurocholate excretion into bile in isolated perfused rat liver

1992 ◽  
Vol 281 (3) ◽  
pp. 593-595 ◽  
Author(s):  
C Hallbrucker ◽  
F Lang ◽  
W Gerok ◽  
D Häussinger
Keyword(s):  
Bile Acid ◽  
Amino Acid ◽  
Cell Volume ◽  
Rat Liver ◽  
Bile Flow ◽  
Cell Swelling ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Volume Changes ◽  
Close Relationship

The effects of aniso-osmotically and amino-acid-induced cell-volume changes on bile flow and biliary taurocholate excretion were studied in isolated perfused rat liver. With taurocholate (100 microM) in the influent perfusate, hypo-osmotic exposure (225 mosmol/l) increased taurocholate excretion into bile and bile flow by 42 and 27% respectively, whereas inhibition by 32 and 47% respectively was observed after hyperosmotic (385 mosmol/l) exposure. The effects of aniso-moticity on taurocholate excretion into bile was observed throughout aniso-osmotic exposure, even after completion of volume-regulatory ion fluxes and were fully reversible upon re-exposure to normo-osmotic media. Hypo-osmotic cell swelling (225 mosmol/l) increased the Vmax. of taurocholate translocation from the sinusoidal compartment into bile about 2-fold. Also, cell swelling induced by glutamine and glycine stimulated both bile flow and biliary taurocholate excretion. There was a close relationship between the aniso-osmotically and amino-acid-induced change of cell volume and taurocholate excretion into bile. The data suggest that liver cell volume plays an important role in regulating bile-acid-dependent bile flow and biliary taurocholate excretion.

scholarly journals Peroxisomal fatty acid oxidation as detected by H2O2 production in intact perfused rat liver

1981 ◽  
Vol 196 (3) ◽  
pp. 705-712 ◽  
Author(s):  
E C Foerster ◽  
T Fährenkemper ◽  
U Rabe ◽  
P Graf ◽  
H Sies
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Rat Liver ◽  
Hydrogen Donor ◽  
High Yield ◽  
Acid Oxidation ◽  
Isolated Perfused Rat Liver ◽  
H2o2 Production ◽  
Perfused Rat Liver ◽  
H2o2 Formation

1. H2O2 formation associated with the metabolism of added fatty acids was quantitatively determined in isolated haemoglobin-free perfused rat liver (non-recirculating system) by two different methods. 2. Organ spectrophotometry of catalase Compound I [Sies & Chance (1970) FEBS Lett. 11, 172-176] was used to detect H2O2 formation (a) by steady-state titration with added hydrogen donor, methanol or (b) by comparison of fatty-acid responses with those of the calibration compound, urate. 3. In the use of the peroxidatic reaction of catalase, [14C]methanol was added as hydrogen donor at an optimal concentration of 1 mM in the presence of 0.2 mM-L-methionine, and 14CO2 production rates were determined. 4. Results obtained by the different methods were similar. 5. The yield of H2O2 formation, expressed as the rate of H2O2 formation in relation to the rate of fatty-acid supply, was less than 1.0 in all cases, indicating that, regardless of chain length, less than one acetyl unit was formed per mol of added fatty acid by the peroxisomal system. In particular, the standard substrate used with isolated peroxisomal preparations (C16:0 fatty acid) gave low yield (close to zero). Long-chain monounsaturated fatty acids exhibit a relatively high yield of H2O2 formation. 6. The hypolipidaemic agent bezafibrate led to slightly increased yields for most of the acids tested, but the yield with oleate was decreased to one-half the original yield. 7. It is concluded that in the intact isolated perfused rat liver the assayable capacity for peroxisomal beta-oxidation is used to only a minor degree. However, the observed rates of H2O2 production with fatty acids can account for a considerable share of the endogenous H2O2 production found in the intact animal.

Cell-swelling-induced taurine release from isolated perfused rat liver

1994 ◽  
Vol 72 (1-2) ◽  
pp. 8-11 ◽  
Author(s):  
H. S. Brand ◽  
A. J. Meijer ◽  
L. A. Gustafson ◽  
G. G. A. Jörning ◽  
A. C. J. Leegwater ◽  
...  
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Cell Swelling ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Liver Mass ◽  
Taurine Release ◽  
Perfusion Medium ◽  
Nacl Concentration ◽  
Isolated Liver

Astrocytes and lymphocytes are able to release significant amounts of taurine during periods of hypotonicity to reduce the increase in cell volume. To investigate this mechanism in the liver, we studied the release of free amino acids from isolated perfused rat liver during hypotonicity. The osmolarity of the perfusion medium was reduced from 305 to 255 or 205 mosM by decreasing the NaCl concentration 25 or 50 mM, respectively. This induced an 6–8% increase in liver mass and was associated with a specific 1.7-fold (−50 mosM) and 14-fold (−100 mosM) increase of the taurine release. None of the other amino acids measured showed a significant increase in their concentration in the effluent. The increase in taurine release occurred within 30 s after exposure to hypotonicity (maximal after 1–1.5 min) and followed closely the changes in liver mass. The taurine release declined gradually during successive exposures of the isolated liver to −100 mosM. This release was 29 and 17% of the original during the second and third exposure, respectively.Key words: cell swelling, liver, taurine.

A Comparison of Plasminogen Activators Derived from Rat Plasma, Primary Rat Hepatocytes and Isolated Perfused Rat Liver

1982 ◽  
Vol 47 (02) ◽  
pp. 166-172 ◽  
Author(s):  
Yoav Sharoni ◽  
Maria C Topal ◽  
Patricia R Tuttle ◽  
Henry Berger
Keyword(s):  
Rat Liver ◽  
Isoelectric Point ◽  
Rat Hepatocytes ◽  
Cell Types ◽  
Plasminogen Activators ◽  
Rat Plasma ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Molecular Weights ◽  
Physiological Relevance

SummaryOf the two cell types it was possible to culture from the dissociated rat liver, hepatocytes and Kupffer cells, only the former were fibrinolytically active. Rat hepatocytes during the first 24 hr in culture secreted two plasminogen activators with molecular weights identical to those found in rat plasma, an 80,000-dalton form (PA-80) and a 45,000-dalton form (PA-45). Partially purified preparations of plasminogen activators from both sources were subjected to isoelectric focusing (IEF) to compare characteristics further. There were three distinct peaks of PA-45 in each preparation with isoelectric points of 7.1, 7.2 and 7.4; all electrophoretic forms had the same low affinity to fibrin. PA-80 from both sources displayed similar IEF profiles with forms ranging from pH values of 7 to 8, all with the same high affinity to fibrin. The major form of PA-80 in the plasma preparation had an isoelectric point of 7.9 whereas that in the hepatocyte preparation had an isoelectric point of 7.6. The isolated perfused rat liver was also shown to produce both PA-80 and PA-45 emphasizing the physiological relevance of the findings with hepatocytes. It is concluded that in the rat hepatocytes contribute to the plasma profile with regard to the plasminogen activator content.

Troxerutin protects the isolated perfused rat liver from a possible lipid peroxidation by coumarin

Phytomedicine ◽  
2005 ◽  
Vol 12 (1-2) ◽  
pp. 52-61 ◽  
Author(s):  
B.S. Adam ◽  
R. Pentz ◽  
C.P. Siegers ◽  
O. Strubelt ◽  
M. Tegtmeier
Keyword(s):  
Lipid Peroxidation ◽  
Rat Liver ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver

scholarly journals Influence of Kynurenate on Cholesterol and Fatty Acid Synthesis in Isolated Perfused Rat Liver

1973 ◽  
Vol 248 (2) ◽  
pp. 738-739
Author(s):  
Christian A. Barth ◽  
H. Jürgen Hackenschmidt ◽  
Elmar E. Weis ◽  
Karl F.A. Decker
Keyword(s):  
Fatty Acid ◽  
Rat Liver ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver
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