A study of some enzymes of glycerolipid biosynthesis in rat liver after subtotal hepatectomy

Mangiapane, E H; Lloyd-Davies, K A; Brindley, David N.

doi:10.1042/bj1340103

Cited by 105 publications

(58 citation statements)

References 30 publications

(6 reference statements)

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“…Triacylglycerol synthesis, at least from preformed fatty acids, is increased after resection of part of the liver, as may be demonstrated with labelled fatty acids (Fex & Olivecrona, 1968a;Olivecrona & Fex, 1970;Fex, 1970a) or glycerol (Olivecrona & Fex, 1970). This synthesis of extra triacylglycerols (per unit mass of tissue), which occurs in the absence of any extra phospholipid synthesis (Fex, 1970b;Girard et al, 1971), may be Vartly a result of increased activity of phosphatidate phosphohydrolase (Mangiapane et al, 1973). Rates of export of triacylglycerol are maintained during re-growth, i.e.…”

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confidence: 90%

Fatty acid synthesis in the regenerating liver of the rat

Gove¹,

Hems²

1978

Biochemical Journal

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1. Synthesis de novo of fatty acids in the rat liver, measured per g wet wt. of tissue, was increased by a factor of about two, between 1 and 4 days after partial hepatectomy, compared with rates in sham-operated control rat livers. 2. There were no associated changes in the rates ofliver cholesterol synthesis or of adipose-tissue fatty acid synthesis in rats after partial hepatectomy, compared with rates in sham-operated rats. 3. In regenerating livers, perfused under three different conditions, there was no alteration in the capacity for fatty acid synthesis compared with that of control rats. 4. The increased synthesis of fatty acids in regenerating liver was associated with insignificant increases in plasma concentrations oftriacylglycerols and free fatty acids, with a decrease in content of liver glycogen, and with no change in hepatic activity of acetyl-CoA carboxylase. 5. The accelerated rate ofsynthesis offatty acids in regenerating liver appears not to be due to any intrinsic alteration in hepatic capacity for fatty acid synthesis, but it may be caused by the continuous action on liver of unidentified circulating factors.

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confidence: 90%

Fatty acid synthesis in the regenerating liver of the rat

Gove¹,

Hems²

1978

Biochemical Journal

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“…To do this for the microsomal activities, it was necessary to correct for the recovery of endoplasmic-reticulum membranes in this fraction relative to the homogenate in which the DNA concentration was measured (Mangiapane et al, 1973). This was done by using both arylesterase and glucose 6-phosphatase as endoplasmic-reticulum markers.…”

Section: Resultsmentioning

confidence: 99%

“…CDP-diacylglycerol (prepared from eggs) was obtained from Miles Laboratories, Stoke Poges, Slough SLI 3NW, Bucks., U.K. All radiochemicals were purchased from The Radiochemical Centre, Amersham, Bucks., U.K. Streptozotocin was a gift from the Drug Development Branch, Division of Cancer Treatment, National Cancer Institute, Bethesda, MD, U.S.A. sn-1,2-Diacylglycerol was prepared essentially by the method described by Mangiapane et al (1973). The starting material was crude egg lecithin, which was obtained from Sigma (London) Chemical Co., Kingston-upon-Thames, Surrey, U.K.…”

Section: Methodsmentioning

confidence: 99%

“…Preparation ofthe microsomal andparticle-free supernatant fractions These were prepared as described by Mangiapane et al (1973). The samples of the particle-free supernatant fractions, which were used to measure the phosphatidate phosphohydrolase activity (EC 3.1.3.4), were dialysed for about 16h at 4°C against 0.3M-sucrose, adjusted to pH7.4 with KHCO3 and containing 0.5 mM-dithiothreitol.…”

Section: Induction Ofexperimental Diabetesmentioning

confidence: 99%

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The effect of chronic diabetes, induced by streptozotocin, on the activities of some enzymes of glycerolipid synthesis in rat liver

1978

Biochemical Journal

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1. Rats were injected with a single dose of 35mg of streptozotocin/kg body wt. They exhibited a diabetes that was characterized by glycosuria, polyuria, polydipsia, hyperphagia, hyperglycaemia, increased concentrations of unesterified fatty acids, glycerol and triacylglycerols in the serum and an increased activity of glucose 6-phosphatase in the liver. 2. After 10 weeks the hepatic activities of the microsomal glycerol phosphate acyltransferase, phosphatidate phosphohydrolase, phosphatidate cytidylyltransferase, diacylglycerol acyltransferase, choline phosphotransferase, CDP-diacylglycerol-inositol phosphatidyltransferase and the soluble phosphatidate phosphohydrolase were measured. 3. The only significant changes were an increase in the activity of the soluble phosphatidate phosphohydrolase and a decrease in that of the CDP-diacylglycerolinositol phosphatidyltransferase in the diabetic rats. 4. These results are discussed in relation to the control of glycerolipid synthesis.Diabetes mellitus is characterized by hyperglycaemia, which is often accompanied by glycosuria, and by an increase in the consumption of food and water and in urine output. In severe cases there is ketonaemia, ketonuria and hypertriglyceridaemia. The last is usually caused by an accelerated secretion of very-low-density lipoprotein, and the severity of the hypertriglyceridaemia can be taken as an indication of the adequacy of the control of the diabetes (Nikkila & Kekki, 1973;Nikkila, 1974).In the present study rats were made chronically diabetic by a single injection of streptozotocin. These animals were then used to investigate whether the diabetic state is accompanied by changes in the relative activities of the enzymes responsible for the synthesis ofglycerolipids in the liver. It is hoped that these results will add to our understanding of how glycerolipid synthesis is controlled.

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“…VAVRECKA et al (17) reported that fasting caused a decrease in the activity of acyl-CoA glycerol phosphate acyltransferase in liver homogenates, and an increase in the activity of phosphatidate phosphohydrolase in the supernatant fraction of the liver. Though the phosphatidate phosphohydro lase activity may play a key role in the regulation of endogenous TG formation under such conditions as an accelerated liver TG formation (hepatoectomy (18), high carbohydrate intake (19-21)), the observation in the fasting state is difficult to interpret since most investigators have reported a decrease in neutral lipid formation under this situation (7,21). Therefore, control of PC biosynthesis in fasted rats by the phosphorylcholine-glyceride transferase could be expected and, consequently, the activity of this enzyme could affect the synthesis of liver TG in fasted rats, if this enzyme was rate-limiting.…”

Section: Discussionmentioning

confidence: 99%

Glycerolipid metabolism in cellular and subcellular fractions of fasted rat liver.

Imaizumi

Sugano

1975

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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SummaryThe effect of overnight fasting on glycerolipids of the rat liver organelles was studied. The concentration of microsomal phospholipids was markedly decreased by fasting, whereas that of mitochondria and whole liver increased significantly. The significant increase due to fasting in the activity of microsomal phosphorylcholine-glyceride transferase appeared to be responsible for the increased concentration of hepatic phospholipid . Th e incorporation by the liver slice of [1-14C] glycerol into PC3 in mito chondria was increased by fasting, while there was no difference in the microsomal fraction containing supernatant. The significant decrease in the relative proportions of oleic and linoleic acids and a significant increase in stearic and arachidonic acids in phos phatidylcholine were observed in the intact liver as well as its subcellular fractions. The possible relationship of these changes after fasting to th e similarity in the incorporation pattern of [l-14C] glycerol into the molecula r species of these glycerolipids was demonstrated .Considerable but equivocal information is available concerning the effect of fasting on the concentration of hepatic lipids in rats (1-6) . In the previous ex periments in which the effect of fasting was examined systematically , we have shown that overnight fasting produces a significant increase in hepatic PC and PE but not TG In the liver of male rats (7) . An attempt to determine the fatty acid composition of hepatic subcellular fractions in fasted rats was done by ALLMA N et al. (3) and ROGERS (6). These investigators were , however, concerned only with total lipids or total phospholipids , and not with each class of glycerolipids in

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A study of some enzymes of glycerolipid biosynthesis in rat liver after subtotal hepatectomy

Cited by 105 publications

References 30 publications

Fatty acid synthesis in the regenerating liver of the rat

Fatty acid synthesis in the regenerating liver of the rat

The effect of chronic diabetes, induced by streptozotocin, on the activities of some enzymes of glycerolipid synthesis in rat liver

Glycerolipid metabolism in cellular and subcellular fractions of fasted rat liver.

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