scholarly journals Comparison of the metabolism of chylomicrons and chylomicron remnants by the perfused liver

1978 ◽  
Vol 170 (1) ◽  
pp. 47-55 ◽  
Author(s):  
R S Gardner ◽  
P A Mayes
Keyword(s):  
Fatty Acids ◽  
Relative Density ◽  
Large Fraction ◽  
Hepatic Metabolism ◽  
Cholesteryl Esters ◽  
Perfused Liver ◽  
Lipoprotein Particle ◽  
Chylomicron Remnants

1. The hepatic metabolism of chylomicrons and chylomicron remnants was compared after adding approximately equal numbers of each lipoprotein particle to the perfusate of isolated livers. 2. At least 40% of the added remnants were metabolized by the liver compared with less than 3% for chylomicrons. 3. There was significantly more net removal of labelled remnants than of chylomicrons by the liver. 4. A greater proportion of labelled cholesterol than of labelled triacylglycerol fatty acids was transferred to the liver from each lipoprotein. 5. Cholesteryl esters of remnants were hydrolysed to triacylglycerol fatty lipoprotein. 5. Cholesteryl esters of remnants were hydrolysed to triacylglycerol fatty acids of remnants were oxidized to CO2 more extensively than those of chylomicrons. 6. There was greater oxidation of remnant glycerolipic [(1(-14)C]oleate than of glycerolipid [1(-14)C]palmitate. 7. A large fraction of the fatty acids of remnants, but not of chylomicrons, was transferred to phospholipids, which were released by the liver in a lipoprotein of relative density less than 1.006. 8. Label from remnants, but not from chylomicrons, was found in lipoproteins of relative density greater than 1.006, which were not released during perfusion but could be flushed out from the liver at the end of perfusion.

Splanchnic metabolism of volatile fatty acids in the dairy cow

2005 ◽  
Vol 80 (1) ◽  
pp. 3-10 ◽  
Author(s):  
N. B. Kristensen
Keyword(s):  
Fatty Acids ◽  
Dairy Cow ◽  
Volatile Fatty Acids ◽  
Large Fraction ◽  
Hepatic Metabolism ◽  
Future Research ◽  
Peripheral Tissues ◽  
Nutritional Physiology ◽  
Ruminal Epithelium ◽  
Gastro Intestinal Tract

AbstractVolatile fatty acids (VFA) are quantitatively important substrates for dairy cows and other ruminants. It has been a central dogma in the nutritional physiology of ruminants that the ruminal epithelium metabolizes a large fraction of VFA during theirabsorption and consequently a relatively small fraction of VFA is available for peripheral tissues including the mammary gland. New data on splanchnic metabolism of VFA indicate that the ruminal epithelium metabolizes none or small amounts of acetate and propionate absorbed from the rumen. However, the ruminal epithelium has a large fractional uptake of butyrate and valerate during their absorption from the rumen. The liver takes up proportionately 0·9 or more of the absorbed propionate, however multiple factors are involved in regulation of hepatic metabolism and propionate does not determine glucose availability to the cowper se. In light of the quantitative importance of VFA to the dairy cow it is important that future research attempts to bridge the gap between the biology of food degradation/digestion in the gastro-intestinal tract and availability of specific nutrients to the cow which impact intermediary metabolism and nutrient utilizationin productive tissues.

scholarly journals Glycogen synthesis in the perfused liver of adrenalectomized rats

1976 ◽  
Vol 156 (3) ◽  
pp. 585-592 ◽  
Author(s):  
P D Whitton ◽  
D A Hems
Keyword(s):  
Intact Animal ◽  
Glycogen Synthesis ◽  
Hepatic Metabolism ◽  
Hepatic Glycogen ◽  
Perfused Liver ◽  
Short Term ◽  
Glycogen Accumulation ◽  
Glycogen Deposition ◽  
Adrenalectomized Rats

1. A total loss of capacity for net glycogen synthesis was observed in experiments with the perfused liver of starved adrenalectomized rats. 2. This lesion was corrected by insulin or cortisol in vivo (over 2-5h), but not by any agent tested in perfusion. 3. The activity of glycogen synthetase a, and its increase during perfusion, in the presence of glucose plus glucogenic substrates, were proportional to the rate of net glycogen accumulation. 4. This complete inherent loss of capacity for glycogen synthesis after adrenalectomy is greater than any defect in hepatic metabolism yet reported in this situation, and is not explicable by a decrease in the rate of gluconegenesis (which supports glycogen synthesis in the liver of starved rats). The short-term (2-5h) stimulatory effect of glucocorticoids in the intact animal, on hepatic glycogen deposition, may be mediated partly through insulin action, although neither insulin or cortisol appear to act directly on the liver to stimulate glycogen synthesis.

Gas chromatographic separation of cholesteryl esters of fatty acids of different degrees of unsaturation

Lipids ◽  
1977 ◽  
Vol 12 (2) ◽  
pp. 228-232 ◽  
Author(s):  
Toru Takagi ◽  
Akira Sakai ◽  
Yutaka Itabashi ◽  
Kenji Hayashi
Keyword(s):  
Fatty Acids ◽  
Chromatographic Separation ◽  
Cholesteryl Esters ◽  
Gas Chromatographic Separation

Optical anisotropy of some cholesteryl esters of fatty acids

Pramana ◽  
1984 ◽  
Vol 23 (5) ◽  
pp. 639-643 ◽  
Author(s):  
H S Subramhanyam ◽  
Upkar Singh Hunjan
Keyword(s):  
Fatty Acids ◽  
Optical Anisotropy ◽  
Cholesteryl Esters

Chylomicron remnant uptake by enterocytes is receptor dependent

1996 ◽  
Vol 270 (1) ◽  
pp. G203-G212 ◽  
Author(s):  
M. Soued ◽  
C. M. Mansbach
Keyword(s):  
Fatty Acids ◽  
Low Density Lipoprotein ◽  
Basolateral Membrane ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Receptor Associated Protein ◽  
Ldl Uptake ◽  
Proximal Intestine ◽  
Chylomicron Remnants ◽  
Glyceryl Trioleate

During glyceryl trioleate absorption in the rat, mucosal triacylglycerol (TG) fatty acids have been shown to consist of only 71% exogenous oleate. Chylomicron remnants are enriched with endogenous TG fatty acids, compared with their parent chylomicrons, which consist primarily of exogenous TG fatty acids. Because enterocytes have the apolipoprotein B-100/E receptor, this study was directed at determining whether the cells can take up and metabolize chylomicron remnants and, if so, whether this was receptor mediated. Isolated enterocytes were incubated with purified 3H-labeled chylomicron remnants. The remnants were shown to be taken up by the basolateral membrane, not the apical membrane. Remnant uptake was proportional to time and number of enterocytes, and saturation kinetics were observed. Nonradiolabeled remnants, human low-density lipoprotein (LDL), anti-LDL receptor antibody, and receptor-associated protein, an LDL-related receptor inhibitor, were all shown to compete for or reduce 3H-remnant uptake. Remnants taken up by the enterocytes could not be removed on incubation with excess human LDL. Uptake was shown to be greatest in the villus tips of the proximal intestine. These studies suggest that enterocytes take up chylomicron remnants by a receptor-mediated process from their basolateral membranes and that the remnants could provide a source of endogenous TG fatty acids for the enterocytes.

scholarly journals The incorporation of linoleic acid into the plasma lipids of sheep given intraruminal infusions of maize oil or free linoleic acid

1969 ◽  
Vol 23 (3) ◽  
pp. 709-714 ◽  
Author(s):  
R. C. Noble ◽  
W. Steele ◽  
J. H Moore
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Linoleic Acid ◽  
Plasma Lipids ◽  
Cholesteryl Esters ◽  
Absorption Mechanism ◽  
Plasma Triglycerides ◽  
Direct Incorporation ◽  
Maize Oil ◽  
Fatty Acid Compositions

1. The fatty acid compositions of the plasma cholesteryl esters, phospholipids, triglycerides and unesterilied fatty acids were determined in two sheep at various times after they had been given intraruminal infusions of emulsions of maize oil or linoleic acid.2. The concentration of linoleic acid in the plasma triglycerides began to increase 3 h after infusion began. The infusions of maize oil and linoleic acid resulted in the appearance of peak concentrations of linoleic acid in the plasma triglycerides 6 and 12h respectively after infusion began.3. After the infusion of maize oil the plasma triglycerides showed an increasein theconcentration of stearic acid but after the infusion of linoleic acid the plasma triglycerides showed an increase in the concentration of oleic acid.4. The concentration of linoleic acid in the plasma phospholipids and cholesteryl esters did not begin to increase until 6–9 h and 24–25 h respectively after the infusions had begun.5. No evidence was found for an absorption mechanism which involved the direct incorporation of linoleic acid into the blood phospholipids or cholesteryl esters.

EFFECT OF ESTRADIOL AND TESTOSTERONE ON THE FATTY ACIDS OF PLASMA CHOLESTERYL ESTERS AND PHOSPHOLIPIDS IN THE CASTRATED RAT

1964 ◽  
Vol 42 (3) ◽  
pp. 365-376 ◽  
Author(s):  
R. L. Lyman ◽  
Angela Shannon ◽  
Rosemarie Ostwald ◽  
P. Miljanich
Keyword(s):  
Fatty Acids ◽  
Arachidonic Acid ◽  
Palmitic Acid ◽  
Phospholipid Fatty Acid ◽  
Male Rats ◽  
Cholesteryl Esters ◽  
Phospholipid Fatty Acid Composition ◽  
Plasma Phospholipids ◽  
Plasma Cholesteryl Ester ◽  
Arachidonic Acids

The effects of physiological doses of estradiol and testosterone on plasma cholesteryl ester and phospholipid fatty acid composition were investigated in castrated male rats. The animals were killed after 3 weeks on experiment, and their plasma cholesteryl esters and phospholipids were analyzed and compared with those of intact female and male rats.Estradiol appeared to be responsible for the increased proportion of plasma cholesteryl arachidonate seen in the female or estrogen-injected rats since the proportion of cholesteryl arachidonate in castrated control rats was lower and similar to that of male or testosterone-treated rats. Plasma phospholipids of female and estradiol-injected rats had a higher percentage of stearic acid relative to palmitic acid. On the other hand, male, castrated control and testosterone-treated rats had higher proportions of palmitic acid. Fractionation of the plasma phospholipids into cephalins, lecithins, sphingomyelins, and lysolecithins, and analyses of their fatty acids, revealed that a principal effect of estradiol was to increase proportions and amounts of stearic and arachidonic acids in the lecithin fraction.The results suggest that estradiol may influence the synthesis of a lecithin rich in stearic and arachidonic acid. A possible relationship between the arachidonic-acid-rich lecithin and the higher percentage of cholesteryl arachidonate in estradiol-treated rats is discussed.

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