scholarly journals Arachidonic acid inhibits glycine transport in cultured glial cells

1990 ◽  
Vol 271 (1) ◽  
pp. 237-242 ◽  
Author(s):  
F Zafra ◽  
R Alcantara ◽  
J Gomeza ◽  
C Aragon ◽  
C Gimenez
Keyword(s):  
Fatty Acids ◽  
Arachidonic Acid ◽  
Unsaturated Fatty Acids ◽  
Membrane Vesicle ◽  
Selective Inhibition ◽  
Inhibitory Effect ◽  
C6 Glioma Cells ◽  
Plasma Membrane Vesicle ◽  
Glycine Uptake ◽  
Glycine Transport

The effects of arachidonic acid on glycine uptake, exchange and efflux in C6 glioma cells were investigated. Arachidonic acid produced a dose-dependent inhibition of high-affinity glycine uptake. This effect was not due to a simple detergent-like action on membranes, as the inhibition of glycine transport was most pronounced with cis-unsaturated long-chain fatty acids, whereas saturated and trans-unsaturated fatty acids had relatively little or no effect. Endogenous unsaturated non-esterified fatty acids may exert a similar inhibitory effect on the transport of glycine. The mechanism for this inhibitory effect has been examined in a plasma membrane vesicle preparation derived from C6 cells, which avoids metabolic or compartmentation interferences. The results suggest that part of the selective inhibition of glycine transport by arachidonic acid could be due to the effects of the arachidonic acid on the lipid domain surrounding the carrier.

Selective Inhibition of Thromboxane Synthetase with Dazoxiben - Basis of Its Inhibitory Effect on Platelet Adhesion

1983 ◽  
Vol 49 (02) ◽  
pp. 096-101 ◽  
Author(s):  
V C Menys ◽  
J A Davies
Keyword(s):  
Arachidonic Acid ◽  
Platelet Adhesion ◽  
Fold Increase ◽  
Selective Inhibition ◽  
Inhibitory Effect ◽  
Selective Inhibitor ◽  
Coated Glass ◽  
Thromboxane Synthetase ◽  
Pre Treatment

SummaryPlatelet adhesion to rabbit aortic subendothelium or collagen-coated glass was quantitated in a rotating probe device by uptake of radio-labelled platelets. Under conditions in which aspirin had no effect, dazoxiben, a selective inhibitor of thromboxane synthetase, reduced platelet adhesion to aortic subendothelium by about 40% but did not affect adhesion to collagen-coated glass. Pre-treatment of aortic segments with 15-HPETE, a selective inhibitor of PGI2-synthetase, abolished the inhibitory effect of dazoxiben on adhesion. Concentrations of 6-oxo-PGFlα in the perfusate were raised in the presence of dazoxiben alone, and following addition of thrombin (10 units/ml) there was a 2-3 fold increase in concentration. Perfusion of damaged aorta with platelets labelled with (14C)-arachidonic acid in the presence of thrombin and dazoxiben resulted in the appearance of (14C)-labelled-6-oxo-PGFiα. Inhibition of thromboxane synthetase limits platelet adhesion probably by promoting vascular synthesis of PGI2 from endoperoxides liberated from adherent platelets, which subsequently promotes detachment of cells from the surface.

β-Subunit–Dependent Modulation of hSlo BK Current by Arachidonic Acid

2007 ◽  
Vol 97 (1) ◽  
pp. 62-69 ◽  
Author(s):  
X. Sun ◽  
D. Zhou ◽  
P. Zhang ◽  
E. G. Moczydlowski ◽  
G. G. Haddad
Keyword(s):  
Fatty Acids ◽  
Arachidonic Acid ◽  
Conformational Changes ◽  
Unsaturated Fatty Acids ◽  
Saturated Fatty Acids ◽  
Nordihydroguaiaretic Acid ◽  
Bk Channels ◽  
Bk Channel ◽  
Β Subunit ◽  
Α Subunit

In this study, we examined the effect of arachidonic acid (AA) on the BK α-subunit with or without β-subunits expressed in Xenopus oocytes. In excised patches, AA potentiated the hSlo-α current and slowed inactivation only when β2/3 subunit was co-expressed. The β2-subunit–dependent modulation by AA persisted in the presence of either superoxide dismutase or inhibitors of AA metabolism such as nordihydroguaiaretic acid and eicosatetraynoic acid, suggesting that AA acts directly rather than through its metabolites. Other cis unsaturated fatty acids (docosahexaenoic and oleic acid) also enhanced hSlo-α + β2 currents and slowed inactivation, whereas saturated fatty acids (palmitic, stearic, and caprylic acid) were without effect. Pretreatment with trypsin to remove the cytosolic inactivation domain largely occluded AA action. Intracellularly applied free synthetic β2-ball peptide induced inactivation of the hSlo-α current, and AA failed to enhance this current and slow the inactivation. These results suggest that AA removes inactivation by interacting, possibly through conformational changes, with β2 to prevent the inactivation ball from reaching its receptor. Our data reveal a novel mechanism of β-subunit–dependent modulation of BK channels by AA. In freshly dissociated mouse neocortical neurons, AA eliminated a transient component of whole cell K+ currents. BK channel inactivation may be a specific mechanism by which AA and other unsaturated fatty acids influence neuronal death/survival in neuropathological conditions.

Unsaturated fatty acids and cyclooxygenase inhibitors: effects on pial arterioles

1982 ◽  
Vol 242 (4) ◽  
pp. H629-H632
Author(s):  
W. I. Rosenblum
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Eicosatrienoic Acid ◽  
Inhibitory Effect ◽  
Cyclooxygenase Inhibitors ◽  
Dependent Manner ◽  
Double Bonds ◽  
Pial Arterioles ◽  
Dose Dependent

Cerebral surface arterioles of the mouse were constricted in a dose-dependent manner by three different unsaturated fatty acids each with one of its double bonds in the n-6 position: arachidonate, linoleic, and 11,14,17-eicosatrienoic acid (ETA) in doses of 10-200 micrograms/ml. The constriction was transient, and its magnitude was significantly reduced by pretreatment of the mice with intraperitoneal injections of indomethacin (5 mg/kg), aspirin (100 mg/kg), or sodium 2-amino-3-(4 chlorobenzyl)-phenylacetate (AHR-6293, 100 mg/kg). The inhibitory effect of these cyclooxygenase inhibitors suggests that this enzyme is involved in the response to these fatty acids and is in keeping with suggestions in the literature stating that such unsaturated fatty acids may interact with cyclooxygenase even when they cannot form prostaglandin (PG) endoperoxides, The PG endoperoxide formed by arachidonate or the analogous hydroperoxy compounds formed by linoleic or 11,14,17 ETA, may then alter cerebrovascular tone by production of reactive, O2-containing species. Alternate explanations for the data are also proposed.

Inhibitory Effect Of Exogenous Arachidonic Acid Or Linoleic Acid On Rabbit Platelet Aggregation And Release Reaction

1981 ◽  
Author(s):  
M Cattaneo ◽  
R L Kinlough-Rathbone ◽  
J F Mustard
Keyword(s):  
Arachidonic Acid ◽  
Linoleic Acid ◽  
Platelet Aggregation ◽  
Cell Membrane ◽  
Platelet Function ◽  
Unsaturated Fatty Acids ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Lipoxygenase Pathway ◽  
High Concentrations

In contrast to other release-inducing agents (e.g. thrombin) arachidonic acid (AA) releases only 40-50% of amine storage granule contents and although low concentrations induce aggregation, high concentrations do not. Several theories have been proposed to explain these observations: 1) AA or its products inactivates the cyclo-oxygenase; 2) the products of AA increase platelet cAMP; 3) lipoxygenase products are inhibitory; 4) unsaturated fatty acids (UFA) perturb the cell membrane. Using washed rabbit platelets we examined the effect of AA on platelet function. In these experiments aspirin-treated platelets (ASA 5.5 mM) were exposed to AA (230 μM) for 15 min. and then to PGEj (10 μM) for 30 min. The platelets were then resuspended. These platelets did not aggregate to ADP (9 μM) and their response to thrombin (0.02-0.05 U/ml) was impaired in contrast to control, ASA-treated platelets not exposed to AA. Non-ASA-treated platelets exposed to AA (230 μM), deaggre- gated with PGE1, and then resuspended also did not aggregate in response to ADP (9 μM) collagen, AA (230 μM) or thrombin (0.02-0.05 U/ml). When platelets pretreated with ASA and AA were mixed 1:1 with normal platelets and the mixture stimulated with AA (230 μM), the AA-treated platelets did not release their granule contents whereas the normal platelets did. These results do not support the hypothesis- that the inhibitory effect of AA on platelet aggregation and release is primarily due to inhibition of cyclo-oxygenase or an increase in cAMP caused by AA products. It seems unlikely that inhibition by AA can be due to products of the lipoxygenase pathway, because the effect persists when the platelets are washed and resuspended. Similar results were obtained by incubating platelets with linoleic acid (230 μM). This evidence is compatible with the hypothesis that UFA can inhibit platelet function by perturbing the cell membrane. This effect may be related to changes in receptor availability.

scholarly journals Inhibitory effects of some long-chain unsaturated fatty acids on mitochondrial β-oxidation. Effects of streptozotocin-induced diabetes on mitochondrial β-oxidation of polyunsaturated fatty acids

1985 ◽  
Vol 230 (2) ◽  
pp. 329-337 ◽  
Author(s):  
H Osmundsen ◽  
K Bjørnstad
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Reductase Activity ◽  
Liver Mitochondria ◽  
Inhibitory Effect ◽  
Diabetic Rats ◽  
Inhibitory Property ◽  
Streptozotocin Induced Diabetes ◽  
Streptozotocin Diabetic Rats ◽  
Coa Reductase

Evidence showing that some unsaturated fatty acids, and in particular docosahexaenoic acid, can be powerful inhibitors of mitochondrial β-oxidation is presented. This inhibitory property is, however, also observed with the cis- and trans-isomers of the C18:1(16) acid. Hence it is probably the position of the double bond(s), and not the degree of unsaturation, which confers the inhibitory property. It is suggested that the inhibitory effect is caused by accumulation of 2,4-di- or 2,4,7-tri-enoyl-CoA esters in the mitochondrial matrix. This has previously been shown to occur with these fatty acids, in particular when the supply of NADPH was limiting 2,4-dienoyl-CoA reductase (EC 1.3.1.-) activity [Hiltunen, Osmundsen & Bremer (1983) Biochim. Biophys. Acta 752, 223-232]. Liver mitochondria from streptozotocin-diabetic rats showed an increased ability to β-oxidize 2,4-dienoyl-CoA-requiring acylcarnitines. Docosahexaenoylcarnitine was also found to be less inhibitory at lower concentrations with incubation under coupled conditions. With uncoupling conditions there was little difference between mitochondria from normal and diabetic rats in these respects. This correlates with a 5-fold stimulation of 2,4-dienoyl-CoA reductase activity found in mitochondria from streptozotocin-diabetic rats.

scholarly journals Effect of 5-trans isomer of arachidonic acid on model liposomal membranes studied by a combined simulation and experimental approach

2018 ◽  
Author(s):  
Ioanna Tremi ◽  
Dimitrios Anagnostopoulos ◽  
Ellas Spyratou ◽  
Paraskevi Gkeka ◽  
Alexandros G. Georgakilas ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Arachidonic Acid ◽  
Free Radicals ◽  
Lipid Bilayers ◽  
Unsaturated Fatty Acids ◽  
Md Simulations ◽  
Γ Irradiation ◽  
Physiological Concentration ◽  
Increased Risk ◽  
Average Size

AbstractUnsaturated fatty acids are found in humans predominantly in the cis configuration. Fatty acids in the trans configuration are primarily the result of human processing (trans fats), but can also be formed endogenously by radical stress. The cis-trans isomerization of fatty acids by free radicals could be connected to several pathologies. Trans fats have been linked to an increased risk of coronary artery disease; however, the reasons for the resulting pathogenesis remain unclear. Here, we investigate the effect of a mono trans isomer of arachidonic acid (C20:4-5trans,8cis,11cis,14cis) produced by free radicals in physiological concentration on a model erythrocyte membrane using a combined experimental and theoretical approach. Molecular Dynamics (MD) simulations of two model lipid bilayers containing arachidonic acid and its 5-trans isomer in 3% mol. were carried out for this purpose. The 5-trans isomer formation in the phospholipids was catalyzed by HOCH2CH2S• radicals, generated from the corresponding thiol by γ-irradiation, in multilamellar vesicles (MLVs) of SAPC. Large unilamellar vesicles were made by the extrusion method (LUVET) as a biomimetic model for cis-trans isomerization. Atomic Force Microscopy and Dynamic Light Scattering were used to measure the average size, morphology, and the z-potential of the liposomes. Both results from MD simulations and experiments are in agreement and indicate that the two model membranes display different physicochemical properties in that the bilayers containing the trans fatty acids were more ordered and more rigid than those containing solely the cis arachidonic acid. Correspondingly, the average size of the liposomes containing trans isomers was smaller than the ones without.

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