Chronic alcohol feeding and its withdrawal on the structure and function of the rat liver plasma membrane: a study with 125I-labelled glucagon binding as a metabolic probe

1982 ◽  
Vol 60 (9) ◽  
pp. 1171-1176 ◽  
Author(s):  
Hung Lee ◽  
E. A. Hosein
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Structure And Function ◽  
Scatchard Analysis ◽  
Chronic Alcohol ◽  
Alcohol Administration ◽  
Liver Plasma Membranes ◽  
And Function ◽  
Chronic Alcohol Administration

The effect of chronic alcohol administration on the structure and function of the rat liver plasma membranes has been investigated. Chronic alcohol administration did not affect the yield of these membranes using conventional isolation procedures. The extent of plasma membrane enrichment or contamination with other interior membranes was identical in the control and alcoholic preparations. The binding of 125I-labelled glucagon to these experimental liver plasma membranes was significantly decreased. Scatchard analysis of the high affinity sites showed a significant reduction [Formula: see text] in receptor number rather than binding affinity, which was not altered. This anomaly persisted through 72-h withdrawal of alcohol. These data suggest that very stable changes were induced in these liver plasma membranes after prolonged alcohol ingestion.

scholarly journals ISOLATION OF RAT LIVER PLASMA MEMBRANES

1970 ◽  
Vol 47 (3) ◽  
pp. 604-618 ◽  
Author(s):  
Oscar Touster ◽  
N. N. Aronson ◽  
John T. Dulaney ◽  
Herman Hendrickson
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Preparative Method ◽  
Membrane Localization ◽  
Plasma Membrane Localization ◽  
Liver Plasma Membranes ◽  
Nucleotide Pyrophosphatase ◽  
Rat Liver Plasma Membranes

Nucleotide pyrophosphatase and phosphodiesterase I of rat liver have been found to be localized primarily in cell particulates highly enriched with respect to the most commonly accepted plasma membrane marker, 5'-nucleotidase, and therefore should themselves be assigned a plasma membrane localization. The observation that plasma membranes sediment in isotonic sucrose with both nuclear and microsomal fractions was exploited to obtain plasma membrane preparations from each fraction. Both preparations are similar in chemical and enzymic composition. Moreover, the preparative method developed in this study appears to give the best combination of yield, purity, and reproducibility available. The question of the possible identity of nucleotide pyrophosphatase and phosphodiesterase I is considered, and evidence is presented suggesting that these activities may be manifestations of the same enzyme.

scholarly journals Alkaline ribonuclease and phosphodiesterase activity in rat liver plasma membranes

1973 ◽  
Vol 132 (3) ◽  
pp. 449-458 ◽  
Author(s):  
Terence D. Prospero ◽  
Malcolm L. E. Burge ◽  
Kenneth A. Norris ◽  
Richard H. Hinton ◽  
Eric Reid
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Gradient Centrifugation ◽  
Ribonuclease Activity ◽  
Nuclear Fraction ◽  
Phosphodiesterase Activity ◽  
Ph Optimum ◽  
Liver Plasma Membranes ◽  
Rat Liver Plasma Membranes

The ribonuclease and phosphodiesterase activities of rat liver plasma membranes, purified from the crude nuclear fraction by centrifugation in an A-XII zonal rotor and flotation, were examined and compared. The plasma membrane is responsible for between 65 and 90% of the phosphodiesterase activity of the cell and between 25 and 30% of the particulate ribonuclease activity measured at pH8.7 in the presence of 7.5mm-MgCl2. Both enzymes were most active between pH8.5 and 8.9. Close to the pH optimum, both enzymes were more active in Tris buffer than in Bicine or glycine buffer. Both plasma-membrane phosphodiesterase and ribonuclease were strongly activated by Mg2+, there being at least a 12-fold difference between the activity in the presence of Mg2+ and of EDTA. There is, however, a difference in the response of the enzymes to Mg2+ and EDTA in that the phosphodiesterase is fully activated by 1.0mm-MgCl2 and fully inhibited by 1.0mm-EDTA, whereas the ribonuclease requires 7.5mm-MgCl2 for full activation and 5mm-EDTA for full inhibition. Density-gradient centrifugation has indicated that on solubilization in Triton X-100 most of the ribonuclease activity is released into a small fragment of the same size as that containing the phosphodiesterase activity. The relationship between the two activities is discussed in view of these results.

scholarly journals The microviscosity of liver plasma membranes of rats fed with oleoylanilide

1984 ◽  
Vol 218 (1) ◽  
pp. 125-129 ◽  
Author(s):  
R Pagani ◽  
M T Portoles ◽  
F G Gavilanes ◽  
P Garcia-Barreno ◽  
A M Municio
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Fluorescence Polarization ◽  
Plasma Membranes ◽  
Fluorescence Probe ◽  
Isolated Hepatocytes ◽  
Polarization Parameter ◽  
Lipid Interactions ◽  
Liver Plasma Membranes

Oleoylanilide was administered orally to groups of rats according to different patterns. Oleoylanilide was perfused at different concentrations through rat liver. Oleoylanilide was added to isolated hepatocytes. Oleoylanilide was added to plasma-membrane preparations. Membrane preparations were obtained after experiments performed in vivo and perfusion experiments and, by using 1,6-diphenylhexa-1,3,5-triene as fluorescence probe, the fluorescence polarization parameter was measured, from which the microviscosity (eta) was calculated. In all cases the microviscosity decreased markedly. Addition of oleoylanilide to hepatocyte preparations and to isolated membranes produced the same effect, increasing the fluidity of the membranes. These data suggest that oleoylanilide partitions into the membrane, disordering some lipid interactions.

scholarly journals Structure and Function of the Plasma Membrane

1968 ◽  
Vol 52 (1) ◽  
pp. 257-278 ◽  
Author(s):  
Edward D. Korn
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Current Knowledge ◽  
Structure And Function ◽  
Attractive Alternative ◽  
Membrane Function ◽  
Classical Models ◽  
And Function ◽  
Direct Attack ◽  
Membrane Biosynthesis

The paucimolecular unit membrane model of the structure of the plasma membrane is critically reviewed in relation to current knowledge of the chemical and enzymatic composition of isolated plasma membranes, the properties of phospholipids, the chemistry of fixation for electron microscopy, the conformation of membrane proteins, the nature of the lipid-protein bonds in membranes, and possible mechanisms of transmembrane transport and membrane biosynthesis. It is concluded that the classical models, although not disproven, are not well supported by, and are difficult to reconcile with, the data now available. On the other hand, although a model based on lipoprotein subunits is, from a biochemical perspective, an attractive alternative, it too is far from proven. Many of the questions may be resolved by studies of membrane function and membrane biosynthesis rather than by a direct attack on membrane structure.

Adaptive changes in rat liver plasma membranes after chronic alcohol administration and its subsequent withdrawal

1986 ◽  
Vol 64 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Hung Lee ◽  
E. A. Hosein
Keyword(s):  
Plasma Membranes ◽  
Membrane Lipids ◽  
Buoyant Density ◽  
Fatty Acyl ◽  
Chronic Alcohol ◽  
Alcohol Administration ◽  
Rat Liver Plasma Membranes ◽  
Subsequent Withdrawal ◽  
Induced Changes ◽  
Chronic Alcohol Administration

Rat hepatic plasma membranes isolated after chronic alcohol feeding displayed a different buoyant density range with a significantly increased peak density value when spun isopycnically in a 30–50% sucrose (w/w) gradient. This change persisted up to 48 h of withdrawal from alcohol. Analysis of membrane lipids revealed certain significant alterations in the phospholipids as well as the fatty acyl composition in individual phospholipids of the experimental plasma membranes. During withdrawal of alcohol for 48 h, all the alcohol-induced changes in the phospholipids returned to normal. Most initial changes in fatty acids reverted to the control composition during this time, but new changes in fatty acyl distribution were also observed. These were interpreted to represent readaptation to the withdrawal of the alcohol. It is not established how long this readaptation period lasts.

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