Early alterations in rat liver chromatin structure after a single dose of diethylnitrosamine

In the chromatin of 24-h regenerating rat livers, derivative melting profiles are characterized by a high proportion of transitions above 90°C. After the injection of diethylnitrosamine there is a rapid shift to lower melting temperatures. This is due to a rearrangement of the chromatin to higher amounts of nucleosomal components but possibly also a consequence of chemical modifications and conformational alterations of the DNA. In the nonregenerating liver essentially the same observations can be made, although reactions proceed significantly slower. These results are in good agreement with the observation that carcinogens are more active in tissues stimulated to rapid proliferation as compared to resting tissues.

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Structure of Chromatin DNA not Complexed with Protein

Zeitschrift für Naturforschung C ◽

10.1515/znc-1974-9-1024 ◽

1974 ◽

Vol 29 (9-10) ◽

pp. 597-601 ◽

Cited By ~ 3

Author(s):

K. Hartmut Richter ◽

Constantin E. Sekeris

Keyword(s):

Rat Liver ◽

Chromatin Structure ◽

Dnase I ◽

Hydroxy Apatite ◽

Free Dna ◽

Liver Chromatin ◽

Total Dna ◽

The Mean ◽

Phosphate Groups

Abstract Rat liver chromatin was titrated by poly-ᴅ-lysine of mol.wt. 140,000. Approximately 32% of the phosphate groups of the chromatin were found to react with the polycation. By submitting the chromatin-poly-ᴅ-lysine complex to pronase and DNase I digestion and by further submitting the obtained DNA-lysine complex to hydroxy-apatite-chromatography, "free" DNA was isolated. The mean S-value of this DNA was found to be 10 ± 0 .8 , corresponding to approximately 2100 nucleo tide pairs, its renaturation kinetics similar to total DNA. On the basis of these results and on the findings that histone-saturated DNA-histone recombinates are digested with DNase I up to 65% a model of chromatin structure was proposed, taking into account protein covered-and free DNA regions

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Lectins as probes of chromatin structure. Binding of concanavalin A to purified rat liver chromatin.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)66934-6 ◽

1977 ◽

Vol 252 (20) ◽

pp. 7062-7067

Author(s):

W B Rizzo ◽

M Bustin

Keyword(s):

Rat Liver ◽

Concanavalin A ◽

Chromatin Structure ◽

Liver Chromatin

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Hepatic uptake of intact glutathione S-conjugate, inhibition by organic anions, and sinusoidal catabolism

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1993.265.3.g547 ◽

1993 ◽

Vol 265 (3) ◽

pp. G547-G554

Author(s):

C. A. Hinchman ◽

A. T. Truong ◽

N. Ballatori

Keyword(s):

Guinea Pig ◽

Rat Liver ◽

Marked Decrease ◽

Hepatic Uptake ◽

Half Time ◽

High Concentrations ◽

Rat Livers ◽

Dose Dependent ◽

Uptake And Metabolism ◽

Guinea Pig Liver

To identify potential mechanisms for hepatic removal of circulating glutathione (GSH) conjugates, uptake and metabolism of S-2,4-dinitrophenylglutathione (DNP-SG) were examined in isolated perfused livers from rat and guinea pig. Guinea pig livers perfused with 5 mumol of DNP-SG in a recirculating system (50 microM initial concn) rapidly cleared the conjugate from the perfusate (half time 3.7 min), whereas clearance was considerably slower in rat liver (half time 35 min). Disappearance of DNP-SG from the perfusate was accompanied by a simultaneous appearance of DNP-SG and its metabolites in bile. Addition of acivicin, an inhibitor of gamma-glutamyltransferase (gamma-GT), to the perfusate resulted in a marked decrease in DNP-SG clearance by guinea pig liver but had no effect in rat liver, suggesting that in the guinea pig this process is largely dependent on sinusoidal gamma-GT activity. However, even in the presence of acivicin, rat and guinea pig livers removed nearly one-half of the administered DNP-SG from the recirculating perfusate over 30 min. High concentrations of DNP-SG were found in bile (up to 3.7 mM), indicating that the liver is capable of transporting the intact conjugate from the circulation. When rat livers were perfused with higher concentrations of DNP-SG (100 and 250 microM), biliary excretion of DNP-SG increased dose dependently, with concentrations in bile reaching 10 mM at the higher dose. This was accompanied by a dose-dependent choleresis.(ABSTRACT TRUNCATED AT 250 WORDS)

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Influence of Slice Thickness and Culture Conditions on the Metabolism of 7-Ethoxycoumarin in Precision-cut Rat Liver Slices

Alternatives to Laboratory Animals ◽

10.1177/026119299802600417 ◽

1998 ◽

Vol 26 (4) ◽

pp. 541-548

Author(s):

Roger J. Price ◽

Anthony B. Renwick ◽

Paula T. Barton ◽

J. Brian Houston ◽

Brian G. Lake

Keyword(s):

Gas Phase ◽

Rat Liver ◽

Xenobiotic Metabolism ◽

Culture Conditions ◽

Slice Thickness ◽

Dependent Manner ◽

Sprague Dawley ◽

Liver Slices ◽

Sprague Dawley Rats ◽

Rat Livers

This study investigated the effects of some experimental variables on the rate of xenobiotic metabolism in precision-cut rat liver slices. Liver slices of 123 ± 8μm (mean ± SEM of six slices), 165 ± 3μm, 238 ± 6μm and 515 ± 14μm thickness were prepared from male Sprague-Dawley rats, and incubated in RPMI 1640 medium in an atmosphere of 95% O2/5% CO2 by using a dynamic organ culture system. Liver slices of all thicknesses metabolised 10μM 7-ethoxycoumarin to total (free and conjugated) 7-hydroxycoumarin in a time-dependent manner. The rate of 7-ethoxycoumarin metabolism was greatest in 165μm thick slices and slowest in 515μm thick slices, being 2.74 ± 0.19pmol/minute/mg slice protein and 0.69 ± 0.07pmol/minute/mg slice protein, respectively. No marked effects on the rate of 7-ethoxycoumarin metabolism in liver slices were observed either by changing the medium to Earle's balanced salt solution (EBSS) or by changing the gas phase to 95% air/5% CO2. Moreover, the perfusion of rat livers with EBSS at 2–4°C, prior to preparation of tissue cores, did not enhance 7-ethoxycoumarin metabolism in rat liver slices. In this study, the optimal slice thickness was 175μm, with higher rates of 7-ethoxycoumarin metabolism being observed than with 250μm thick slices, which are often used for studies of xenobiotic metabolism. Variable results were obtained with slices of around 100–120μm thickness, which may be attributable to the ratio between intact hepatocytes and cells damaged by the slicing procedure in these very thin slices.

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An explanation for decreased ketogenesis in the liver of the obese Zucker rat

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1989.257.4.r822 ◽

1989 ◽

Vol 257 (4) ◽

pp. R822-R828 ◽

Cited By ~ 2

Author(s):

M. J. Azain ◽

J. A. Ontko

Keyword(s):

Fatty Acid ◽

Fatty Acid Oxidation ◽

Rat Liver ◽

Intact Cell ◽

Zucker Rats ◽

Acid Oxidation ◽

Palmitate Oxidation ◽

Malonyl Coa ◽

Obese Zucker Rats ◽

Rat Livers

These studies were undertaken to further characterize and explain the differences in hepatic fatty acid metabolism between lean and obese Zucker rats. It was shown that the rate of palmitate or octanoate oxidation and the inhibition of palmitate oxidation by malonyl CoA in mitochondria isolated from lean and obese Zucker rats were similar. Cytochrome oxidase activity was similar in lean and obese rat livers. It was found that the addition of cytosol from the obese rat liver inhibited palmitate oxidation by 20-30% in mitochondria isolated from lean or obese rat livers and thus reproduced the conditions observed in the intact cell. Increased concentrations of metabolites such as malonyl CoA and glycerophosphate in the liver of the obese rat are likely contributors to this inhibitory effect. These results are extrapolated to the intact cell and suggest that decreased hepatic fatty acid oxidation in the obese rat can be accounted for by cytosolic influences on the mitochondria. The decreased rate of fatty acid oxidation observed in the intact hepatocyte or perfused liver cannot be explained by a defect in the capacity of mitochondria to oxidize substrate or by a decrease in mitochondrial number in the obese rat liver.

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