Albumin synthesis by the perfused rat liver A comparison of methods with special reference to the effect of dietary protein deprivation

1971 ◽  
Vol 124 (5) ◽  
pp. 833.b1-833.b1
Author(s):  
R Hoffenberg ◽  
A H Gordont ◽  
E G Black
Keyword(s):  
Special Reference ◽  
Rat Liver ◽  
Dietary Protein ◽  
Perfused Rat Liver ◽  
Comparison Of Methods ◽  
Albumin Synthesis ◽  
Protein Deprivation

Effect of alcohol on albumin synthesis by the isolated perfused rat liver

1973 ◽  
Vol 26 (11) ◽  
pp. 1191-1194 ◽  
Author(s):  
Ralph E. Kirsch ◽  
Lesley O’C. Frith ◽  
Robin H. Stead ◽  
Stuart J. Saunders
Keyword(s):  
Rat Liver ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Albumin Synthesis

The Anti-Anabolic Effect of Glucagon on Albumin Synthesis by the Isolated Perfused Rat Liver

1973 ◽  
Vol 45 (3) ◽  
pp. 13P-13P
Author(s):  
A. S. Tavill ◽  
Joan Metcalfe ◽  
Elizabeth Black ◽  
R. Hoffenberg
Keyword(s):  
Rat Liver ◽  
Isolated Perfused Rat Liver ◽  
Anabolic Effect ◽  
Perfused Rat Liver ◽  
Albumin Synthesis

scholarly journals The effect of dietary protein deficiency on albumin synthesis and on the concentration of active albumin messenger ribonucleic acid in rat liver

1978 ◽  
Vol 172 (1) ◽  
pp. 129-135 ◽  
Author(s):  
V M Pain ◽  
M J Clemens ◽  
P J Garlick
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Dietary Protein ◽  
Liver Protein ◽  
Albumin Synthesis ◽  
Deficient Diet ◽  
Messenger Ribonucleic Acid ◽  
Cytoplasmic Rna ◽  
Reticulocyte Lysate ◽  
Albumin Mrna

In rats fed on a protein-deficient diet, albumin synthesis as a percentage of total liver protein synthesis falls from the normal value of approx. 15% to about 8%. We have extracted total cytoplasmic RNA from individual rat livers and measured the concentration of active albumin mRNA by translation in a reticulocyte lysate system from which the endogenous mRNA had been removed [Pelham & Jackson (1976) Eur. J. Biochem. 67, 247-256]. In this messenger-dependent system it is possible to measure the synthesis of albumin as a proportion of the overall protein synthesis promoted by the addition of the hepatic RNA. The results show that the concentration of translatable albumin mRNA in samples of total cytoplasmic RNA from livers of protein-deficient rats is decreased markedly. These findings suggest that dietary protein supply affects selectively the synthesis and/or functional stability of albumin mRNA in rat liver.

scholarly journals Plasma protein catabolism by the perfused rat liver. The effect of alteration of albumin concentration and dietary protein depletion

1970 ◽  
Vol 118 (3) ◽  
pp. 401-404 ◽  
Author(s):  
R. Hoffenberg ◽  
A. H. Gordon ◽  
E. G. Black ◽  
L. N. Louis
Keyword(s):  
Rat Liver ◽  
Dietary Protein ◽  
Plasma Proteins ◽  
Normal Values ◽  
Isolated Perfused Rat Liver ◽  
Albumin Concentration ◽  
Perfused Rat Liver ◽  
Plasma Albumin ◽  
Degradation Rates ◽  
Parenchymal Cells

1. The isolated perfused rat liver was used to study degradation rates of plasma albumin, transferrin and fibrinogen. 2. Constant fractional rates were observed for all three proteins even when the albumin concentration was drastically increased by the addition of large amounts to the perfusate pool. 3. Livers taken from rats deprived of dietary protein for 14–18 days showed greatly diminished fractional catabolic rates for albumin when perfused with blood from similarly deprived animals. 4. These rates could be restored to near-normal values by adding albumin or by perfusing with blood from normally fed rats. 5. These findings are consistent with the theory of pinocytosis as a step in the degradation of plasma proteins by hepatic parenchymal cells.

scholarly journals The effects of amino acids on albumin synthesis by the isolated perfused rat liver

1972 ◽  
Vol 129 (4) ◽  
pp. 805-809 ◽  
Author(s):  
L. Kelman ◽  
S. J. Saunders ◽  
S. Wicht ◽  
L. Frith ◽  
A. Corrigall ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rat Liver ◽  
Normal Values ◽  
Isolated Perfused Rat Liver ◽  
Perfused Rat Liver ◽  
Albumin Synthesis ◽  
Isoleucine Leucine ◽  
Blood Concentrations ◽  
Normal Peripheral Blood

Albumin synthesis was measured in the isolated perfused rat liver by using the livers of both well-fed and starved rats. Starvation markedly decreased albumin synthesis. The livers from starved rats were unable to increase synthesis rates after the addition to the perfusates of single amino acids or the addition of both glucagon and tryptophan. Arginine, asparagine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, threonine, tryptophan and valine, added together to ten times their normal peripheral blood concentrations, restored synthesis rates to normal. The plasma aminogram (i.e. the relative concentrations, of amino acids) was altered by depriving rats of protein for 48h. The use of blood from the deprived rats as perfusate, instead of normal blood, decreased albumin synthesis rates significantly by livers obtained from well-fed rats. The addition of single amino acids, including the non-metabolizable amino acid, α-aminoisobutyric acid, to the above mixture increased albumin synthesis rates to normal values. It is concluded that amino acids play an important role in the control of albumin synthesis and that more than one mechanism is probably involved.

Plasma Albumin Synthesis in Perfused Rat Liver

1968 ◽  
pp. 100-108
Author(s):  
Joseph Katz ◽  
Alvin L. Sellers ◽  
George Bonorris
Keyword(s):  
Rat Liver ◽  
Perfused Rat Liver ◽  
Albumin Synthesis ◽  
Plasma Albumin

scholarly journals Hepatic albumin and urea synthesis: The mathematical modelling of the dynamics of [14C]carbonate-derived guanidine-labelled arginine in the isolated perfused rat liver

1975 ◽  
Vol 150 (3) ◽  
pp. 495-509 ◽  
Author(s):  
A S Tavill ◽  
D Nadkarni ◽  
J Metcalfe ◽  
E Black ◽  
R Hoffenberg ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Rat Liver ◽  
Specific Radioactivity ◽  
Compartmental Analysis ◽  
Constant Infusion ◽  
Isolated Perfused Rat Liver ◽  
Urea Synthesis ◽  
Perfused Rat Liver ◽  
Albumin Synthesis ◽  
Product Analysis

A mathematical model was constructed to define the dynamics of incorporation of radioactivity into urea carbon and the guanidine carbon of arginine in plasma albumin after the rapid intraportal-venous administration of Na214CO3 in the isolated perfused rat liver. 2. The model was formulated in terms of compartmental analysis and additional experiments were designed to provide further information on subsystem dynamics and to discriminate between alternative model structures. 3. Evidence for the rapid-time-constant of labelling of intracellular arginine was provided by precursor-product analysis of precursor [14C]carboante and product [14C]urea in the perfusate. 4. Compartmental analysis of the dynamics of newly synthesized urea was based on the fate of exogenous [13C]urea, endogenous [14C]urea and the accumulation of [12C]urea in perfusate water, confirming the early completion of urea carbon labelling, the absence of continuing synthesis of labelled urea, and the presence of a small intrahepatic urea-delay pool. 5. Analysis of the perfusate dynamics of endogenously synthesized and exogenously administered [6-14C]arginine indicated that although the capacity for extrahepatic formation of [14C]-urea exists, little or no arginine formed within the intrahepatic urea cycle was transported out of the liver. However, the presence of a rapidly turning-over intrahepatic arginine pool was confirmed. 6. On the basis of these subsystem analyses it was possible to offer feasible estimations for the parameters of the mathematical model. However, it was not possible to stimulate the form and magnitude of the dynamics of newly synthesized labelled urea and albumin which were simultaneously observed after administration of [14C]carbonate on the basis of a preliminary model which postulated that both products were derived from a single hepatic pool of [16-14C]arginine. On the other hand these observed dynamics could be satisfied to a two-compartment arginine model, which also provided an explanation for discrepancies observed between albumin synthesis measured radioisotopically and immunologically. This was based on a relative overestimation of [14C]urea specific radioactivity resulting from the rapid dynamics of [14C]carbonate and the [14C]urea subsystem relative to the labelled albumin subsystem. The effects of arginine compartmentalization could be minimized in the model by minor slowing of the rate of [14C]carbonate turnover or by constant infusion of [14C]carbonate, both of which permitted valid determination of albumin-synthesis rates.

Catabolism of arginine and ornithine in the perfused rat liver: effect of dietary protein and of glucagon

2000 ◽  
Vol 278 (3) ◽  
pp. E516-E521 ◽  
Author(s):  
Dan O'Sullivan ◽  
John T. Brosnan ◽  
Margaret E. Brosnan
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Dietary Protein ◽  
Reaction Pathway ◽  
Perfused Rat Liver ◽  
Ornithine Aminotransferase ◽  
Dibutyryl Camp ◽  
Similar Extent ◽  
Twofold Increase ◽  
Arginine Catabolism

The rates of oxidation of arginine and ornithine that occurred through a reaction pathway involving the enzyme ornithine aminotransferase (EC 2.6.1.13 ) were determined using14C-labeled amino acids in the isolated nonrecirculating perfused rat liver. At physiological concentrations of these amino acids, their catabolism is subject to chronic regulation by the level of protein consumed in the diet. 14CO2production from [U-14C]ornithine (0.1 mM) and from [U-14C]arginine (0.2 mM) was increased about fourfold in livers from rats fed 60% casein diets for 3–4 days. The catabolism of arginine in the perfused rat liver, but not that of ornithine, is subject to acute regulation by glucagon (10− 7 M), which stimulated arginine catabolism by ∼40%. Dibutyryl cAMP (0.1 mM) activated arginine catabolism to a similar extent. In retrograde perfusions, glucagon caused a twofold increase in the rate of arginine catabolism, suggesting an effect of glucagon on arginase in the perivenous cells.

Effects of fasting and alloxan diabetes on albumin synthesis by perfused rat liver

1961 ◽  
Vol 201 (1) ◽  
pp. 55-57 ◽  
Author(s):  
Julian B. Marsh
Keyword(s):  
Cell Suspension ◽  
Rat Liver ◽  
Alloxan Diabetes ◽  
Diabetic Rats ◽  
Red Cell ◽  
Perfused Rat Liver ◽  
Albumin Synthesis ◽  
Plasma Albumin ◽  
Immunochemical Method

The net synthesis of plasma albumin by the rat liver perfused with a red cell suspension has been studied by a quantitative immunochemical method. Albumin synthesis was decreased by an average of 29% after a 24-hr fast in normal rats. It was also decreased by 41% in alloxan diabetic rats.

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