scholarly journals A study of the interrelationship between the triacylglycerol and protein components of very-low-density lipoproteins using the perfused rat liver

1975 ◽  
Vol 150 (3) ◽  
pp. 315-321 ◽  
Author(s):  
S J Petersburg ◽  
A Madeley ◽  
D S Robinson
Keyword(s):  
Rat Liver ◽  
Low Density Lipoprotein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Density Lipoprotein ◽  
Protein Release ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Perfused Rat Liver ◽  
Very Low Density Lipoproteins ◽  
Protein Components

High and low rates of very-low-density-lipoprotein triacylglycerol release from the perfused rat liver were achieved by using livers taken respectively from animals that had been given fructose for 48h or from animals that had been starved for 18h. 2. The higher rates of very-low-density-lipoprotein triacylglycerol release by the livers of the fructose-fed rats were associated with higher rates of very-low-density-lipoprotein protein release. 3. When the livers were perfused in the presence of [3H]leucine, radioactivity was incorporated into the very-low-density-lipoprotein apoproteins. The higher rates of very-low-density-lipoprotein triacylgycerol and protein release by the livers of fructose-fed rats were associated with a greater total incorporation of radioactivity into those apoproteins that entered the running gel during polyacrylamide-gel electrophoresis. However, the distribution of radioactivity among the various apoproteins was not significantly changed by the dietary treatments used.

Concentration-dependent effects of eicosapentaenoic acid on very low density lipoprotein secretion by the isolated perfused rat liver

Lipids ◽  
1993 ◽  
Vol 28 (5) ◽  
pp. 419-425 ◽  
Author(s):  
Zu Jun Zhang ◽  
Henry G. Wilcox ◽  
Lawrence Castellani ◽  
Thomas V. Fungwe ◽  
Marshall B. Elam ◽  
...  
Keyword(s):  
Eicosapentaenoic Acid ◽  
Rat Liver ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Isolated Perfused Rat Liver ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Perfused Rat Liver ◽  
Lipoprotein Secretion

Studies of a Variant Very-Low-Density Lipoprotein with an Acquired Deficiency of Apolipoprotein C-II

1982 ◽  
Vol 62 (1) ◽  
pp. 93-100 ◽  
Author(s):  
J. P. D. Reckless ◽  
J. Stocks ◽  
G. Holdsworth ◽  
D. J. Galton ◽  
A. J. Suggett ◽  
...  
Keyword(s):  
Low Density Lipoprotein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Bovine Milk ◽  
Density Lipoprotein ◽  
Serum Triglyceride ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Myeloma Protein ◽  
Apolipoprotein C

1. A variant very-low-density lipoprotein was associated with severe hypertriglyceridaemia. Urea—polyacrylamide gel electrophoresis of the tetramethylurea-soluble apolipoproteins of these very-low-density lipoproteins (VLDL) showed that the apolipoprotein C-II content was less than 10% of that in VLDL from hypertriglyceridaemic (3–120 mmol/l) controls. 2. VLDL were incubated with bovine milk lipoprotein lipase (LPL) and a 9,10-3H-labelled triglyceride emulsion. The VLDL deficient in apolipoprotein C-II were a poor activator of LPL, compared with the effect of VLDL with normal content of apolipoprotein C-II obtained from either normal or hypertriglyceridaemic sera. 3. The efficacies of various VLDL as substrates for activated LPL were examined. Apolipoprotein C-II-deficient VLDL were a poor substrate for the activated enzyme compared with normal or hypertriglyceridaemic VLDL, and compared with an artificial triglyceride emulsion. 4. The abnormal VLDL were obtained from a subject with an IgG3 lambda myeloma protein. Intravenous infusion of normal plasma containing apolipoprotein C-II was followed by rapid, complete, but short-lived (5–10 days) clearance of serum triglyceride. The effect was observed on three occasions until treatment of the myeloma was effective. 5. The monoclonal protein behaved as a cryoglobulin, and formed large particle complexes with triglyceride-rich lipoproteins, especially at temperatures below 37°C. The apolipoprotein C-II deficiency, and consequent hypertriglyceridaemia, may be secondary to an autoantibody directed against apolipoprotein C-II. VLDL from relatives with hypertriglyceridaemia, but without myeloma, had normal apolipoprotein content, activated LPL, and were efficient substrates for the enzyme.

scholarly journals Effects of oleic acid on the biosynthesis of lipoprotein apoproteins and distribution into the very-low-density lipoprotein by the isolated perfused rat liver

1988 ◽  
Vol 251 (3) ◽  
pp. 809-816 ◽  
Author(s):  
W H Salam ◽  
H G Wilcox ◽  
M Heimberg
Keyword(s):  
Oleic Acid ◽  
Rat Liver ◽  
De Novo ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Isolated Perfused Rat Liver ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Perfused Rat Liver ◽  
Fasted Rats

The effects of oleic acid on the biosynthesis and secretion of VLDL (very-low-density-lipoprotein) apoproteins and lipids were investigated in isolated perfused rat liver. Protein synthesis was measured by the incorporation of L-[4,5-3H]leucine into the VLDL apoproteins (d less than 1.006) and into apolipoproteins of the whole perfusate (d less than 1.21). Oleate did not affect incorporation of [3H]leucine into total-perfusate or hepatic protein. The infusion of oleate, however, increased the mass and radioactivity of the VLDL apoprotein in proportion to the concentration of oleate infused. Uptake of oleate was similar with livers from fed or fasted animals. Fasting itself (24 h) decreased the net secretion and incorporation of [3H]leucine into total VLDL apoprotein and decreased the output of VLDL protein by the liver. A linear relationship existed between the output of VLDL triacylglycerol (mumol/h per g of liver) and secretion and/or synthesis of VLDL protein. Net output of VLDL cholesterol and phospholipid also increased linearly with VLDL-triacylglycerol output. Oleate stimulated incorporation of [3H]leucine into VLDL apo (apolipoprotein) E and apo C by livers from fed animals, and into VLDL apo Bh, B1, E and C by livers from fasted rats. The incorporation of [3H]leucine into individual apolipoproteins of the total perfusate lipoprotein (d less than 1.210 ultracentrifugal fraction) was not changed significantly by oleate during perfusion of livers from fed rats, suggesting that the synthesis de novo of each apolipoprotein was not stimulated by oleate. This is in contrast with that observed with livers from fasted rats, in which the synthesis of the total-perfusate lipoprotein (d less than 1.210 fraction) apo B, E and C was apparently stimulated by oleate. The observations with livers from fed rats suggest redistribution of radioactive apolipoproteins to the VLDL during or after the process of secretion, rather than an increase of apoprotein synthesis de novo. It appears, however, that the biosynthesis of apo B1, Bh, E and C was stimulated by oleic acid in livers from fasted rats. Since the incorporations of [3H]leucine into the VLDL and total-perfusate apolipoproteins were increased in fasted-rat liver when the fatty acid was infused, part of the apparent stimulated synthesis of the VLDL apoprotein may be in response to the increased formation and secretion of VLDL lipid.

Determinants of the uptake of very low density lipoprotein remnants by the perfused rat liver

Metabolism ◽  
1987 ◽  
Vol 36 (11) ◽  
pp. 1106-1113 ◽  
Author(s):  
Cynthia M. Arbeeny ◽  
Vincent A. Rifici ◽  
Dean A. Handley ◽  
Howard A. Eder
Keyword(s):  
Rat Liver ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Perfused Rat Liver

A Comparison of the Secretion of Two Components of Very Low Density Lipoproteins by Perfused Rat Liver

1973 ◽  
Vol 51 (4) ◽  
pp. 490-494 ◽  
Author(s):  
Abraham I. Kook ◽  
David Rubinstein
Keyword(s):  
Rat Liver ◽  
Specific Activity ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Total Radioactivity ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Perfused Rat Liver ◽  
Very Low Density Lipoproteins ◽  
Large Pool

The synthesis and secretion by perfused rat liver of the lipid and protein moieties of the α- and β-lipoprotein-containing components of the very low density lipoproteins was studied, following additions of [3H]palmitate and [14C]leucine to the perfusate. The lipid moieties of both components became labelled early in the perfusion, and had a pattern of labelling similar to that of their protein moieties. The protein of the α-lipoprotein component became labelled at the same time as the lipid. The appearance of the isotope in the β-lipoprotein component was delayed, but it then surpassed that of the α-lipoprotein component in both total radioactivity and specific activity. From these data a working hypothesis has been developed which suggests that the protein but not the lipid of the β-lipoprotein component is incorporated into very low density lipoprotein in the sequence in which it is synthesized, while the α-lipoprotein component is drawn randomly from a large pool.

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