n-3 Fatty Acids and Human Platelets

The thrombin-dependent enrichment of alkenylacyl ethanolamine phosphoglyceride in [14C]eicosapentaenoic acid ([14C]EPA) was demonstrated and compared with [3H]arachidonic acid ([3H]AA) following the simultaneous prelabelling of individual human platelet phospholipids with these two fatty acids. The alkenylacyl, diacyl, and alkylacyl classes of ethanolamine phosphoglycerides (PE) were separated by thin-layer chromatography as their acetylated derivatives after hydrolysis of the parent phospholipid with phospholipase C. The ratios of [3H]/[14C] for the increased radioactivity appearing in alkenylacyl PE following 60 and 120 s of thrombin stimulation were the same as the corresponding ratio (2.0) found in the choline phosphoglycerides (PC) from control (unstimulated) platelets. These results suggest no significant selectivity between EPA and AA in the thrombin-stimulated transfer of these fatty acids from diacyl PC to alkenylacyl PE. The present findings may possibly bear some relevance to the altered platelet reactivity and (or) decreased thromboxane A2 formation observed in human subjects following the ingestion of marine lipid containing EPA.

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Thrombin induces a biphasic 1,2-diacylglycerol production in human platelets

Biochemical Journal ◽

10.1042/bj2750355 ◽

1991 ◽

Vol 275 (2) ◽

pp. 355-361 ◽

Cited By ~ 27

Author(s):

S Nakashima ◽

A Suganuma ◽

A Matsui ◽

Y Nozawa

Keyword(s):

Fatty Acids ◽

Arachidonic Acid ◽

Phosphatidic Acid ◽

Myristic Acid ◽

Time Course ◽

Human Platelets ◽

Second Phase ◽

Mass Content ◽

Small Production ◽

Later Phase

The 1,2-diacylglycerol (DAG) mass content was measured in thrombin-stimulated human platelets. Thrombin stimulates a biphasic accumulation of DAG, with an early phase reaching a peak at 10 s and a later phase reaching a peak at 2-3 min. The time course of first-phase DAG production corresponded well to that of Ins(1,4,5)P3 formation, which was rapid and transient. The second phase of DAG accumulation occurred after the level of Ins(1,4,5)P3 returned to nearly basal. Thrombin stimulated the decrease in PtdIns and phosphatidylcholine contents. The source of second-phase DAG was examined in platelets prelabelled with three radioactive fatty acids, i.e. arachidonic, palmitic and myristic. Thrombin stimulated the increase in radioactivity of DAG with decline of PtdIns in platelets labelled with [3H]arachidonic acid or [3H]palmitic acid, in which PtdIns was considerably labelled. In contrast, significant accumulation of [3H]DAG was not observed in [3H]myristic acid-labelled platelets, in which PtdIns was poorly labelled. In platelets prelabelled with [3H]inositol, an increase in InsP in response to thrombin was seen for more than 5 min. In contrast, upon stimulation, significant increases in [3H]phosphocholine and [3H]choline were not observed in [methyl-3H]choline-labelled platelets. Thrombin induced a small production of phosphatidylethanol, when ethanol was present during stimulation. However, the formation of DAG and phosphatidic acid was not significantly affected by ethanol. These results suggest that thrombin stimulates a biphasic accumulation of DAG, initially from PtdInsP2 and later from PtdIns in human platelets.

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High performance liquid chromatographic determination of fatty acids in phospholipid fraction of human platelets and plasma after administration of eicosapentaenoic acid.

BUNSEKI KAGAKU ◽

10.2116/bunsekikagaku.33.7_e219 ◽

1984 ◽

Vol 33 (7) ◽

pp. E219-E226 ◽

Cited By ~ 2

Author(s):

Mitsuo IKEDA ◽

Kenji SHIMADA ◽

Ushiho MATSUMOTO

Keyword(s):

Fatty Acids ◽

Eicosapentaenoic Acid ◽

High Performance ◽

Chromatographic Determination ◽

High Performance Liquid Chromatographic ◽

Human Platelets ◽

Phospholipid Fraction ◽

Liquid Chromatographic Determination ◽

Liquid Chromatographic

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Influence of Some Plasma Fatty Acids on the Phospholipid Fatty Acid Pattern of Human Platelets – An “Ex Vivo” Experience

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661185 ◽

1984 ◽

Vol 52 (03) ◽

pp. 232-235 ◽

Cited By ~ 7

Author(s):

Juana Vallés ◽

Justo Aznar ◽

M Teresa Santos

Keyword(s):

Fatty Acids ◽

Ex Vivo ◽

Phospholipid Fatty Acid ◽

Fatty Acid Pattern ◽

Plasma Phospholipid ◽

Normal Subjects ◽

Human Platelets ◽

Plasma Lipoproteins ◽

Fa Composition

SummarySome correlations between plasma and platelet fatty acids (FA) were evaluated “ex vivo” in 94 normal subjects.The highest relationships between total FA from plasma and platelets were found for 18:1 (r = 0.74) and 18:2 (r = 0.67). Low correlations were obtained for free fatty acids (FFA). The most significant correlations between fatty acids esterifying plasma and platelet phospholipids were found for the 18:1 (r = 0.66); 18:2 (r = 0.74) and 20:5 (r = 0.66).Our results suggest that the platelet phospholipid FA could be more easily modified by plasma variation in the FA composition of phospholipids than by variations in the plasma FA composition of the FFA fraction. In addition, the incorporation of FA from plasma into the platelet phospholipids “in vivo” may take place through an acylation-deacylation process and also by the incorporation of whole plasma phospholipid molecules into the platelets, probably through an exchange of plasma lipoproteins and platelets. Finally, arachidonic acid seems to have a different and selective way of incorporation into platelet phospholipids.

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Synthesis of two hydroxy fatty acids from 7,10,13,16,19-docosapentaenoic acid by human platelets.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)42615-9 ◽

1984 ◽

Vol 259 (23) ◽

pp. 14413-14417 ◽

Cited By ~ 3

Author(s):

M M Careaga ◽

H Sprecher

Keyword(s):

Fatty Acids ◽

Docosapentaenoic Acid ◽

Human Platelets ◽

Hydroxy Fatty Acids

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Kinetics of Inhibition of ADP-Induced Platelet Aggregation by Dihomo-β-Linolenic Acid (DHLA).

10.1055/s-0039-1684703 ◽

1979 ◽

Author(s):

M. Zuzel ◽

A. Spencer

Keyword(s):

Fatty Acids ◽

Platelet Aggregation ◽

Competitive Inhibition ◽

Human Platelets ◽

Inhibition Of Platelet Aggregation ◽

Kinetics Of ◽

Dose Dependent ◽

Kinetics Of Inhibition ◽

Primary Platelet

In the study of the effects on platelets of thromboxanes and prostaglandins (PG) large amounts of precursor fatty acids have frequently been added to platelet suspensions. In the case of DHLA, this results in a general inhibition of platelet reactions. We have employed kinetic analysis of the inhibition of ADP-induced primary platelet aggregation to estimate the potency, specificity and mode of action of DHLA on human platelets in citrated PRP. Platelet PG production was estimated from formation of malondialdehyde (MDA) and aspirin (ASA) was used to inhibit production-Inhibition of aggregation and MEA formation were dose-dependent and both were observed at DHLA concentrations of 0.1 mM and above. Inhibition of aggregation was of mixed type, consisting of an ASA-sensitive competitive component (K1 ≈ 0.2mM) and an ASA-insensitve component which was non-competitive and dominated inhibition at higher concentrations of DHLA. The KI (DHLA) of the non-competitive component varied from 0.4 to 1.5 mM with different batches of PRP. Other polyunsaturated fatty acids which are not PG precursors, did not cause competitive inhibition but were as potent as DHLA in the non-competitive inhibition of aggregation. The results show that a large part of the inhibition of platelet aggregation by DHLA in vitro is not due to its transformation into an inhibitor of platelet function in the PG production pathway.

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Lipid Content and In Vitro Incorporation of Free Fatty Acids Into Lipids of Human Platelets: The Effect of Storage at 4°C

Blood ◽

10.1182/blood.v38.1.27.27 ◽

1971 ◽

Vol 38 (1) ◽

pp. 27-38 ◽

Cited By ~ 16

Author(s):

MINORU OKUMA ◽

MANFRED STEINER ◽

MARIO BALDINI

Keyword(s):

Fatty Acids ◽

Free Fatty Acids ◽

Lipid Content ◽

Fatty Acid Fraction ◽

Human Platelets ◽

Molar Ratio ◽

Acid Fraction ◽

Total Lipids ◽

Independent Mechanism

Abstract Lipid content and capacity to incorporate in vitro palmitate-1-14C and linoleate-1-14C into lipids was investigated in fresh and stored (4°C) human platelets. Cholesterol and phospholipids decreased 30% during storage for 6 days. Molar ratio of cholesterol to phospholipids and percentage distribution of individual phospholipids were similar in fresh and stored platelets. Palmitate bound to albumin was rapidly transferred by an energy-independent mechanism into a free fatty acid fraction of platelets. From there it was incorporated into glycerides and phospholipids, a process requiring energy. More palmitate than linoleate was incorporated into fatty acids and glycerides of fresh and stored platelets but linoleate exceeded palmitate in its incorporation into phosphatidylethanolamine. Storage of platelets produced the following changes: (1) Incorporation of palmitate into total lipids was significantly reduced but not that of linoleate. (2) Both palmitate and linoleate showed increased incorporation into phosphatidylethanolamine. (3) Incorporation of linoleate into free fatty acids and triglycerides and of palmitate into phosphatidylcholine was reduced.

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