scholarly journals Acute effects of ethanol on the perfused rat liver. Studies on lipid and carbohydrate metabolism, substrate cycling and perfusate amino acids

1979 ◽  
Vol 184 (1) ◽  
pp. 97-106 ◽  
Author(s):  
David L. Topping ◽  
Dallas G. Clark ◽  
Gerald B. Storer ◽  
Rodney P. Trimble ◽  
Richard J. Illman
Keyword(s):  
Amino Acids ◽  
Carbohydrate Metabolism ◽  
Ketone Bodies ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Fold Increase ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Ethanol Infusion ◽  
Glucose Output

1. Livers from fed rats were perfused in situ with whole rat blood containing glucose labelled uniformly with 14C and specifically with 3H at positions 2, 3 or 6. 2. When ethanol was infused at a concentration of 24μmol/ml of blood the rate of utilization was 2.8μmol/min per g of liver. 3. Ethanol infusion raised perfusate glucose concentrations and caused a 2.5-fold increase in hepatic glucose output. 4. Final blood lactate concentrations were decreased in ethanol-infused livers, but the mean uptake of lactate from erythrocyte glycolysis was unaffected. 5. Production of ketone bodies (3‐hydroxybutyrate+3‐oxobutyrate) and the ratio [3‐hydroxybutyrate]/[3‐oxobutyrate] were raised by ethanol. 6. Formation of 3H2O from specifically 3H-labelled glucoses increased in the order [6-3H]<[3-3H]<[2-3H]. Production of 3H2O from [2-3H]glucose was significantly greater than that from [3-3H]glucose in both control and ethanol-infused livers. Ethanol significantly decreased 3H2O formation from all [3H]glucoses. 7. Liver glycogen content was unaffected by ethanol infusion. 8. Production of very-low-density lipoprotein triacylglycerols was inhibited by ethanol and there was a small increase in liver triacylglycerols. Very-low-density-lipoprotein secretion was negatively correlated with the ratio [3‐hydroxybutyrate]/[3‐oxobutyrate]. Perfusate fatty acid concentrations and molar composition were unaffected by perfusion with ethanol. 9. Ethanol decreased the incorporation of [U-14C]glucose into fatty acids and cholesterol. 10. The concentration of total plasma amino acids was unchanged by ethanol, but the concentrations of alanine and glycine were decreased and ([glutamate]+[glutamine]) was raised. 11. It is proposed that the observed effects of ethanol on carbohydrate metabolism are due to an increased conversion of lactate into glucose, possibly by inhibition of pyruvate dehydrogenase. The increase in gluconeogenesis is accompanied by diminished substrate cycling at glucose–glucose 6-phosphate and at fructose 6-phosphate–fructose 1,6-bisphosphate.

Abstract P250: Sphingosine-1-phosphate Receptor Agonist And Very Low-density Lipoprotein Regulate Aldosterone Production Via Lipin-1 In Human Adrenocortical Cells

Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Shinjini Chowdhury ◽  
Vivek Choudhary ◽  
Mrunal Choudhary ◽  
Xunsheng Chen ◽  
Wendy B Bollag
Keyword(s):  
Gene Expression ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Fold Increase ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Lipid Signal ◽  
Aldosterone Production ◽  
Sphingosine 1 Phosphate ◽  
Lipin 1

Aldosterone is considered to be a link between hypertension and obesity; obese individuals have high serum levels of both sphingosine-1-phosphate (S1P) and very low-density lipoprotein (VLDL). S1P has been reported to be a novel stimulator of aldosterone secretion and phospholipase D (PLD) activity. VLDL has also been shown to stimulate aldosterone production in multiple zona glomerulosa cell models via PLD. PLD is an enzyme that hydrolyzes phosphatidylcholine to phosphatidic acid (PA) which can then be converted to diacylglycerol (DAG) by lipin-1. However, it is unclear which of the two lipid signals, PA or DAG, underlies PLD’s mediation of aldosterone production. We hypothesized that the S1P1 receptor (S1PR1) agonist, SEW2871, (and VLDL) induces steroidogenesis and therefore aldosterone production via lipin-1-mediated metabolism of PA to DAG, with our hypothesis focusing on DAG as the key lipid signal produced by PLD (indirectly). In HAC15 cells, lipin-1 was overexpressed using an adenovirus or inhibited using propranolol followed by treatment with or without SEW2871 (or VLDL) for 24 h. Steroidogenic gene expression and aldosterone levels were monitored by qRT-PCR and radioimmunoassay, respectively. We demonstrated that lipin-1 overexpression (OE) enhanced the SEW2871-stimulated 109-fold increase in CYP11B2 expression by 26% while lipin-1 inhibition decreased the SEW2871-stimulated 56-fold increase in CYP11B2 expression by 74%. While lipin-1 OE had no further effect, propranolol reduced SEW2871-stimulated increases in NR4A1 (2-fold) and NR4A2 (9-fold) mRNA levels by 22% and 52% respectively. The SEW2871-stimulated increase in aldosterone production was inhibited by propranolol (53%), although it was not enhanced by lipin-1 OE. Similar results were obtained with VLDL. Our results are, therefore, suggestive of DAG being the key lipid signal since regulating lipin-1 affects S1PR1 agonist- and VLDL-stimulated steroidogenic gene expression and ultimately, aldosterone production. Our study warrants further investigation into these steroidogenic signaling pathways which can lead to the identification of novel therapeutic targets such as lipin-1, or its downstream pathways, to potentially treat obesity-associated hypertension.

scholarly journals Effects of ethynyloestradiol on the metabolism of [1-14C]-oleate by perfused livers and hepatocytes from female rats

1979 ◽  
Vol 180 (2) ◽  
pp. 265-271 ◽  
Author(s):  
Ira Weinstein ◽  
Carlos Soler-Argilaga ◽  
Harold V. Werner ◽  
Murray Heimberg
Keyword(s):  
Fatty Acid ◽  
Ketone Bodies ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Experimental Period ◽  
Female Rats ◽  
Normal Female ◽  
Unesterified Fatty Acid ◽  
Very Low Density Lipoprotein ◽  
Low Density

Normal female rats were given 15μg of ethynyloestradiol/kg body wt. for 14 days and were killed on day 15 after starvation for 12–14h. The livers were isolated and were perfused with a medium containing washed bovine erythrocytes, bovine serum albumin, glucose and [1-14C]oleic acid; 414μmol of oleate were infused/h during a 3h experimental period. The output of bile and the flow of perfusate/g of liver were decreased in livers from animals pretreated with ethynyloestradiol, whereas the liver weight was increased slightly. The rates of uptake and of utilization of [1-14C]oleate were measured when the concentration of unesterified fatty acid in the perfusate plasma was constant. The uptake of unesterified fatty acid was unaffected by pretreatment of the animal with oestrogen; however, the rate of incorporation of [1-14C]oleate into hepatic and perfusate triacylglycerol was stimulated, whereas the rate of conversion into ketone bodies was impaired by treatment of the rat with ethynyloestradiol. Pretreatment of the rat with ethynyloestradiol increased the output of very-low-density lipoprotein triacylglycerol, cholesterol, phospholipid and protein. The production of 14CO2 and the incorporation of radioactivity into phospholipid, cholesteryl ester and diacylglycerol was unaffected by treatment with the steroid. The net output of glucose by livers from oestrogen-treated rats was impaired despite the apparent increased quantities of glycogen in the liver. The overall effect of pretreatment with oestrogen on hepatic metabolism of fatty acids is the channeling of [1-14C]oleate into synthesis and increased output of triacylglycerol as a moiety of the very-low-density lipoprotein, whereas ketogenesis is decreased. The effect of ethynyloestradiol on the liver is apparently independent of the nutritional state of the animal from which the liver was obtained. It is pertinent that hepatocytes prepared from livers of fed rats that had been treated with ethynyloestradiol produced fewer ketone bodies and secreted more triacylglycerol than did hepatocytes prepared from control animals. In these respects, the effects of the steroid were similar in livers from fed or starved (12–14h) rats. Oestrogens may possibly inhibit hepatic oxidation of fatty acid, making more fatty acid available for the synthesis of triacylglycerol, or may stimulate the biosynthesis of triacylglycerol, or may be active on both metabolic pathways.

scholarly journals Insulin and non-esterified fatty acids. Acute regulators of lipogenesis in perfused rat liver

1982 ◽  
Vol 204 (2) ◽  
pp. 433-439 ◽  
Author(s):  
D L Topping ◽  
P A Mayes
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Cholesterol Biosynthesis ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Esterified Fatty Acids ◽  
Equilibrium Concentrations ◽  
Glucose Output

Livers from fed rats were perfused with whole rat blood and infused with oleate to maintain constant concentrations of serum non-esterified fatty acids over a wide physiological range. Infusion of insulin opposed the antilipogenic effects of increasing concentrations of serum non-esterified fatty acids. Secretion of very-low-density-lipoprotein triacylglycerols was directly proportional to the concentration of serum non-esterified fatty acids and was increased by insulin. The secretion of newly-synthesized fatty acids in very-low-density-lipoprotein triacylglycerols decreased with increasing concentrations of serum non-esterified fatty acid. Insulin opposed this change. Cholesterol biosynthesis was unaffected by alterations in concentration of serum non-esterified fatty acid but was increased by insulin. Equilibrium concentrations of perfusate lactate and glucose were increased by serum non-esterified fatty acids but steady-state rates of hepatic glucose output and lactate uptake were unchanged. Insulin decreased perfusate glucose concentrations and abolished the increase in its concentration that resulted from increases in non-esterified fatty acid concentrations.

Studies on the Thromboplastic Effect of Human Plasma Lipoproteins

1976 ◽  
Vol 35 (01) ◽  
pp. 178-185 ◽  
Author(s):  
Helena Sandberg ◽  
Lars-Olov Andersson
Keyword(s):  
High Density Lipoprotein ◽  
Human Plasma ◽  
Platelet Rich Plasma ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Plasma Lipoproteins ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Free Plasma ◽  
Good Agreement

SummaryHuman plasma lipoprotein fractions were prepared by flotation in the ultracentrifuge. Addition of these fractions to platelet-rich, platelet-poor and platelet-free plasma affected the partial thromboplastin and Stypven clotting times to various degrees. Addition of high density lipoprotein (HDL) to platelet-poor and platelet-free plasma shortened both the partial thromboplastin and the Stypven time, whereas addition of low density lipoprotein and very low density lipoprotein (LDL + VLDL) fractions only shortened the Stypven time. The additions had little or no effect in platelet-rich plasma.Experiments involving the addition of anti-HDL antibodies to plasmas with different platelet contents and measuring of clotting times produced results that were in good agreement with those noted when lipoprotein was added. The relation between structure and the clot-promoting activity of various phospholipid components is discussed.

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