Effect of Ionic Strength, pH and Chemical Displacers on the Percentage Protein Binding of Protein-Bound Uremic Toxins

2018 ◽  
Vol 47 (4) ◽  
pp. 351-360 ◽  
Author(s):  
Yuanyuan Shi ◽  
Huajun Tian ◽  
Yifeng Wang ◽  
Yue Shen ◽  
Qiuyu Zhu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Ionic Strength ◽  
Protein Binding ◽  
Free Fatty Acids ◽  
Uremic Toxins ◽  
Ph Change ◽  
Indole 3 Acetic Acid ◽  
Drug Displacement ◽  
Percentage Protein

Background and Objectives: While trying to optimize the dialysis clearances of protein-bound uremic toxins (PBUTs), their percentage protein binding (% PB) is an important parameter. We evaluated the effects of ionic strength, pH change and chemical displacers on the dissociation of PBUTs from albumin in vitro. Methods: PBUTs, such as 3-Carboxy-4-methyl-5-propyl-2-furan-propanoic acid (CMPF), p-cresylsulfate (PCS), indoxyl sulfate (IS) and indole-3-acetic acid (IAA), were spiked with human serum albumin (HSA) solution prepared with different Nacl concentrations and pH values or in the presence of a series of chemical displacers. Ultrafiltration was performed to separate the free and bound fractions, and the % PB of each PBUT was calculated. Results: For all 4 compounds, their % PB decreased with increasing ionic strength, while only slight changes occurred when the pH of the test solution increased from pH 6.0 to pH 8.5; PCS, IS and 3-IAA were relatively easily dissociated from albumin by drug displacement, while CMPF was released from HSA by all studied drugs with difficulty; the PB % for CMPF, PCS, IS and 3-IAA decreased most remarkably in the presence of free fatty acids, such as oleic acid (41.73% for CMPF, 29.9% for PCS, 23.22% for IS, and 20.34% for 3-IAA) and linoleic acid (43.12% for CMPF, 16.65% for PCS, 29.99% for IS, and 16.29% for 3-IAA). Conclusion: The protein binding of PBUTs can be decreased by higher ionic strength, increased pH and the presence of some chemical displacers, including free fatty acids. Effective dialytic removal of PBUTs may be achieved by applying these methods jointly to blood-purification techniques.

scholarly journals Effects of uremic toxins and fatty acids on serum protein binding of furosemide: possible mechanism of the binding defect in uremia

1997 ◽  
Vol 43 (12) ◽  
pp. 2274-2280 ◽  
Author(s):  
Norito Takamura ◽  
Toru Maruyama ◽  
Masaki Otagiri
Keyword(s):  
Fatty Acids ◽  
Protein Binding ◽  
Serum Protein ◽  
Free Fraction ◽  
Drug Binding ◽  
Uremic Toxins ◽  
Serum Protein Binding ◽  
Primary Determinant ◽  
Cascade Effects

Abstract To elucidate the mechanism of impaired serum binding of furosemide observed in patients with renal dysfunction, we examined in vitro the serum protein binding of furosemide in the absence and presence of uremic toxins that are endogenously retained solutes in uremic serum and act as inhibitors of drug binding. Analysis of the binding data of furosemide at its therapeutic concentration (6.6 mg/L) indicated that, among the four uremic toxins studied, 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF) showed the greatest inhibitory potency for the binding of furosemide to serum; moreover, the inhibition was competitive. CMPF thus most likely represents the primary determinant for the serum binding defect of furosemide in uremia. However, CMPF and oleate appear to exert a synergistic effect on the inhibition of furosemide serum binding—perhaps through a cascade effect on furosemide-binding inhibition in the oleate–CMPF–furosemide system, in which the binding of oleate to its low-affinity sites indirectly displaces furosemide from albumin and thus increases the transiently liberated CMPF molecules. Similar cascade effects on furosemide binding in the presence of CMPF were also originated by other long-chain (C18) fatty acids, linoleate and stearate, although to a lesser extent. Because CMPF is not effectively removed by ordinary hemodialysis treatment, the combined direct and cascade effects of CMPF and fatty acids appear to contribute to the increase in the free fraction of furosemide during hemodialysis.

Inhibition of binding of gonadal steroids to serum binding proteins by non-esterified fatty acids: the influence of chain length and degree of unsaturation

1989 ◽  
Vol 120 (2) ◽  
pp. 175-179 ◽  
Author(s):  
C. Street ◽  
R. J. S. Howell ◽  
L. Perry ◽  
S. Al-Othman ◽  
T. Chard
Keyword(s):  
Fatty Acids ◽  
Protein Binding ◽  
Unsaturated Fatty Acids ◽  
Late Pregnancy ◽  
Sex Hormone Binding Globulin ◽  
Partial Purification ◽  
Normal Female ◽  
Esterified Fatty Acids ◽  
Vitro Binding

Abstract. The effect of non-esterified fatty acids (NEFA) on the in vitro binding of testosterone, 5-alpha dihydrotestosterone and estradiol E2 to sex hormone binding globulin (SHBG) was examined using pooled normal female serum, and SHBG and albumin fractions obtained from the partial purification of late pregnancy serum. A range of saturated and unsaturated fatty acids were examined for their effect on steroid-protein binding. In normal female serum, NEFA added at physiological concentrations disrupted steroid-protein binding. The shorter chain (C8–C12) saturated acids and the poly-unsaturated acids proved to be more effective inhibitors than the longer chain saturated or mono-unsaturated acids. The greatest inhibition was obtained with E2 whereas the binding of dihydrotestosterone was least affected. With partially purified SHBG, the same concentrations of NEFA were less effective at inhibiting the binding of dihydrotestosterone and testosterone but elicited the same effect with E2. The binding of steroids to albumin appeared to be unaffected by these concentrations of NEFA.

Free fatty acids normalize a rosiglitazone-induced visfatin release

2006 ◽  
Vol 291 (5) ◽  
pp. E885-E890 ◽  
Author(s):  
Dominik G. Haider ◽  
Friedrich Mittermayer ◽  
Georg Schaller ◽  
Michaela Artwohl ◽  
Sabina M. Baumgartner-Parzer ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Term Treatment ◽  
Double Blind ◽  
Lipid Infusion ◽  
Major Mechanism ◽  
Insulin Mimetic ◽  
Long Term Treatment ◽  
Plasma Ffa

The detrimental effect of elevated free fatty acids (FFAs) on insulin sensitivity can be improved by thiazolidinediones (TZDs) in patients with type 2 diabetes mellitus. It is unknown whether this salutary action of TZD is associated with altered release of the insulin-mimetic adipocytokine visfatin. In this study, we investigated whether visfatin concentrations are altered by FFA and TZD treatment. In a randomized, double-blind, placebo-controlled, parallel-group study 16 healthy volunteers received an infusion of triglycerides/heparin to increase plasma FFA after 3 wk of treatment with rosiglitazone (8 mg/day, n = 8) or placebo ( n = 8), and circulating plasma visfatin was measured. As a corollary, human adipocytes were incubated with synthetic fatty acids and rosiglitazone to assess visfatin release in vitro. The results were that rosiglitazone treatment increased systemic plasma visfatin concentrations from 0.6 ± 0.1 to 1.7 ± 0.2 ng/ml ( P < 0.01). Lipid infusion caused a marked elevation of plasma FFA but had no effect on circulating visfatin in controls. In contrast, elevated visfatin concentrations in subjects receiving rosiglitazone were normalized by lipid infusion. In isolated adipocytes, visfatin was released into supernatant medium by acute addition and long-term treatment of rosiglitazone. This secretion was blocked by synthetic fatty acids and by inhibition of phosphatidylinositol 3-kinase or Akt. In conclusion, release of the insulin-mimetic visfatin may represent a major mechanism of metabolic TZD action. The presence of FFA antagonizes this action, which may have implications for visfatin bioactivity.

Lipid Labelling in Intact Chloroplasts from Exogenous Nucleotide Precursors

1981 ◽  
Vol 36 (1-2) ◽  
pp. 62-70 ◽  
Author(s):  
Margrit Bertrams ◽  
Käthe Wrage ◽  
Ernst Heinz
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
De Novo ◽  
Membrane System ◽  
Chloroplast Envelope ◽  
Label Free ◽  
Intact Chloroplasts ◽  
Time Required

Abstract De novo-synthesis of glycerolipids in chloroplasts is initiated by a stroma enzyme which catalyzes the formation of lyso-phosphatidic acid from glycerophosphate and acyl-CoA. When these substrates are added to isolated, intact chloroplasts, only glycerophosphate can readily pass through the chloroplast envelope which represents a permeation barrier for acyl-CoA, although higher thioester concentrations destroy this membrane system. At low concentrations of acyl-CoA, which do not impair the envelope, intact chloroplasts metabolize exogenous acyl-CoA in two ways to give free fatty acids and labelled phosphatidyl choline. This indicates that the envelope thioesterase can use exogenous substrates. Isolated, intact chloroplasts fixing radioactive CO2 label free fatty acids and acylglycerols but not galactolipids, since they cannot convert 3-phosphoglycerate into UDP-galactose which in vivo is supplied by the cytoplasm. This cooperation was simulated in vitro by adding all enzymes and cofactors necessary for conversion of 3-phosphoglycerate into UDP-galactose to intact chloro­plasts which then formed labelled monogalactosyl diacylglycerol from labelled CO2. The time required to transfer envelope-made galactolipids from the envelope into thylakoids was studied by incubating intact chloroplasts with radioactive UDP-galactose, subsequent osmotic disruption of organelles with concomitant enzymatic degradation of UDP-galactose followed by separation of envelopes and thylakoids. Only after short times (< 1min) appreciable proportions 920-30%) of radioactive galactolipid export from envelopes into thylakoids.

scholarly journals In vitro use of free fatty acids bound to albumin: A comparison of protocols

BioTechniques ◽  
2015 ◽  
Vol 58 (5) ◽  
Author(s):  
Ana F Oliveira ◽  
Daniel A Cunha ◽  
Laurence Ladriere ◽  
Mariana Igoillo-Esteve ◽  
Marco Bugliani ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids

scholarly journals Observations on the pattern on biohydrogenation of esterified and unesterified linoleic acid in the rumen

1974 ◽  
Vol 31 (1) ◽  
pp. 99-108 ◽  
Author(s):  
R. C. Noble ◽  
J. H. Moore ◽  
C. G. Harfoot
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Linoleic Acid ◽  
Free Fatty Acids ◽  
Free Acid ◽  
Octadecenoic Acid ◽  
Conjugated Diene ◽  
Plasma Triglycerides ◽  
Fatty Acid Compositions

1. Studies have been made of the effects of different concentrations of either free or esterified linoleic acid on the biohydrogenation of linoleic acid by rumen micro-organisms in vitro. A comparison has been made with the changes which occurred in the fatty acid compositions of rumen free fatty acids and plasma triglycerides of sheep given intraruminal infusions of linoleic acid or maize oil.2. In the in vitro experiments, with increasing concentrations of 18:2 added as the free fatty acid, a decreasing proportion of this 18:2 was hydrogenated to 18:0 andtrans-11-octadecenoic acid accumulated. The accumulation of large amounts oftrans-11-octadecenoic acid was accompanied in all instances by the accumulation of a conjugated diene identified ascis-9,trans-11-octadecadienoic acid. There appeared to be a product–precursor relationship between the conjugated diene and thetrans-11 monoene.3. When linoleic acid was presented in vitro as the triglyceride, the extent to which hydrogenation occurred was, in all instances, greater than when equivalent amounts of 18:2 were presented as the free acid. Only small amounts of thecis-9,trans-11 diene were detected, and there was no apparent product–precursor relationship between this conjugated diene and the C18monoenoic acids. The C18monoenoic acids that accumulated consisted of bothcisandtransisomers; thecisisomers consisted largely ofcis-9- andcis-11-octadecenoic acids, which together comprised about 30% of the C18monoenoic acids present.4. The infusion of free linoleic acid into the rumen of sheep resulted in an increase in the proportion of total 18:1 and a decrease in the proportions of 16:0 and 18:0 in the total rumen free fatty acids. This increase which occurred in the concentration of 18:1 consisted predominantly of thetrans-11 isomer. A concomitant increase in the concentration of the C18trans-11 acid was observed to occur in the fatty acids of the plasma triglycerides. Infusion of maize oil into the rumen of sheep resulted in little change in the fatty acid compositions of either the free fatty acids in the rumen or the triglycerides of the plasma.5. The findings in vitro and in vivo are discussed with reference to each other and with reference to the possibility that biohydrogenation of 18:2 derived from the triglyceride proceeds by a different pathway from that of 18:2 presented as the free acid.

scholarly journals Effects of dichloroacetate on the metabolism of glucose, pyruvate, acetate, 3-hydroxybutyrate and palmitate in rat diaphragm and heart muscle in vitro and on extraction of glucose, lactate, pyruvate and free fatty acids by dog heart in vivo

1973 ◽  
Vol 134 (4) ◽  
pp. 1067-1081 ◽  
Author(s):  
Anthony McAllister ◽  
S. P. Allison ◽  
Philip J. Randle
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Plasma Free Fatty Acid ◽  
Diabetic Rats ◽  
Inhibitory Effects ◽  
Acetyl Coa ◽  
Citrate Concentration ◽  
Lactate And Pyruvate

1. The extractions of glucose, lactate, pyruvate and free fatty acids by dog heart in vivo were calculated from measurements of their arterial and coronary sinus blood concentration. Elevation of plasma free fatty acid concentrations by infusion of intralipid and heparin resulted in increased extraction of free fatty acids and diminished extractions of glucose, lactate and pyruvate by the heart. It is suggested that metabolism of free fatty acids by the heart in vivo, as in vitro, may impair utilization of these substrates. These effects of elevated plasma free fatty acid concentrations on extractions by the heart in vivo were reversed by injection of dichloroacetate, which also improved extraction of lactate and pyruvate by the heart in vivo in alloxan diabetes. 2. Sodium dichloroacetate increased glucose oxidation and pyruvate oxidation in hearts from fed normal or alloxan-diabetic rats perfused with glucose and insulin. Dichloroacetate inhibited oxidation of acetate and 3-hydroxybutyrate and partially reversed inhibitory effects of these substrates on the oxidation of glucose. In rat diaphragm muscle dichloroacetate inhibited oxidation of acetate, 3-hydroxybutyrate and palmitate and increased glucose oxidation and pyruvate oxidation in diaphragms from alloxan-diabetic rats. Dichloroacetate increased the rate of glycolysis in hearts perfused with glucose, insulin and acetate and evidence is given that this results from a lowering of the citrate concentration within the cell, with a consequent activation of phosphofructokinase. 3. In hearts from normal rats perfused with glucose and insulin, dichloroacetate increased cell concentrations of acetyl-CoA, acetylcarnitine and glutamate and lowered those of aspartate and malate. In perfusions with glucose, insulin and acetate, dichloroacetate lowered the cell citrate concentration without lowering the acetyl-CoA or acetylcarnitine concentrations. Measurements of specific radioactivities of acetyl-CoA, acetylcarnitine and citrate in perfusions with [1-14C]acetate indicated that dichloroacetate lowered the specific radio-activity of these substrates in the perfused heart. Evidence is given that dichloroacetate may not be metabolized by the heart to dichloroacetyl-CoA or dichloroacetylcarnitine or citrate or CO2. 4. We suggest that dichloroacetate may activate pyruvate dehydrogenase, thus increasing the oxidation of pyruvate to acetyl-CoA and acetylcarnitine and the conversion of acetyl-CoA into glutamate, with consumption of aspartate and malate. Possible mechanisms for the changes in cell citrate concentration and for inhibitory effects of dichloroacetate on the oxidation of acetate, 3-hydroxybutyrate and palmitate are discussed.

scholarly journals Free Fatty Acids Impair FGF21 Action in HepG2 Cells

2015 ◽  
Vol 37 (5) ◽  
pp. 1767-1778 ◽  
Author(s):  
Mohamed Asrih ◽  
Christophe Montessuit ◽  
Jacques Philippe ◽  
François R. Jornayvaz
Keyword(s):  
Gene Expression ◽  
Fatty Acids ◽  
Lipid Metabolism ◽  
Free Fatty Acids ◽  
Hepg2 Cells ◽  
Lipid Lowering ◽  
Fibroblast Growth Factor 21 ◽  
Beneficial Effects ◽  
Positive Effects

Background/Aims: Fibroblast growth factor 21 (FGF21) is a key mediator of glucose and lipid metabolism. However, the beneficial effects of exogenous FGF21 administration are attenuated in obese animals and humans with elevated levels of circulating free fatty acids (FFA). Methods: We investigated in vitro how FFA impact FGF21 effects on hepatic lipid metabolism. Results: In the absence of FFA, FGF21 reduced lipogenesis and increased lipid oxidation in HepG2 cells. Inhibition of lipogenesis was associated with a down regulation of SREBP-1c, FAS and SCD1. The lipid-lowering effect was associated with AMPK and ACC phosphorylation, and up regulation of CPT-1α expression. Further, FGF21 treatment reduced TNFα gene expression, suggesting a beneficial action of FGF21 on inflammation. In contrast, the addition of FFA abolished the positive effects of FGF21 on lipid metabolism. Conclusion: In the absence of FFA, FGF21 improves lipid metabolism in HepG2 cells and reduces the inflammatory cytokine TNFα. However, under high levels of FFA, FGF21 action on lipid metabolism and TNFα gene expression is impaired. Therefore, FFA impair FGF21 action in HepG2 cells potentially through TNFα.

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