Change in the lipid status of the erythrocyte membrane in essential hypertension]

The erythrocyte ghosts fatty acid composition of 29 patients with essential hypertension of the II stage were investigated. The significant decrease of some saturated fatty acids as myristic, palmitic and stearic under hypertension was established. Simultaneously the percent of omega-6 arachidonic and docosatrienoic acids substantially increased. At the same time no changes in omega-3 fatty acids were observed. The possible relationship between hypercholesterolemia and erythrocyte membrane fatty acid profile under essential hypertension discussed.     

Changes in the fatty acid profiles of red blood cell membrane phospholipids in human neonates during the first month of life

We have studied the changes in the fatty acid profiles of red blood cell membrane phospholipids in 47 infants who were exclusively fed human milk from birth to 1 month of life. Twenty blood samples were obtained from cord, 15 at 7 days and 12 at 30 days after birth. Membrane phospholipids were obtained from erythrocyte ghosts by thin-layer chromatography and fatty acid composition was determined by gas liquid chromatography. Phosphatidylcholine showed the most important changes during early life; stearic, w6 eicosatrienoic and arachidonic acids decreased whereas oleic and linoleic acids increased. In phosphatidylethanolamine, palmitic and stearic acid declined and oleic, linoleic and docosahexenoic acids increased with advancing age. Small changes were noted for individual fatty acids in phosphatidylserine. In sphingomyelin stearic acid increased from birth to 1 month and linoleic, arachidonic and nervonic acids decreased. Total polyunsaturated fatty acids of the w6 series greater than 18 carbon atoms increased with advancing age in phosphatidylethanolamine and decreased in choline and serine phosphoglycerides and in sphingomyelin. Long chain fatty acids derived from linoleic acid decreased in phosphatidylcholine but increased in ethanolamine and serine phosphoglycerides. The different behavior in the changes observed in fatty acid patterns for each erythrocyte membrane phospholipid may be a consequence of its different location in the cell membrane bilayer and specific exchange with plasma lipid fractions.     

Platelet membrane fatty acids in thrombocytosis due to myeloproliferative disorders

The fatty acid composition of platelet membranes has been analysed in patients with thrombocytosis due to myeloproliferative disorders, who had not taken any drugs. A significant increase in palmitic and oleic acid, together with a decrease in stearic, linoleic and arachidonic acids was observed. The fatty acid pattern of platelet membranes was also analysed in patients during treatment with ASA (acetylsalicylic acid). ASA ingestion completely normalizes the platelet content of palmitic acid and partially that of stearic and arachidonic acid, whereas it has no effect on the level of linoleic acid and raises that of oleic acid. The altered pattern of fatty acids observed in patients may interfere with platelet function by decreasing membrane fluidity. Treatment of patients with ASA seems to act on platelet membranes by partially normalizing the fatty acid composition.     

Selective retention of n-3 and n-6 fatty acids in human milk lipids in the face of increasing proportions of medium chain-length (C10-14) fatty acids

This paper reports the results of our analysis of the impact high levels of de novo fatty acids have on the proportions of essential and non-essential fatty acids in human milk lipids. The data for seven fatty acids (linoleic, alpha-linolenic, arachidonic (AA), docosahexaenoic (DHA), palmitic, stearic and oleic) were derived from several studies conducted in Nigeria. The proportion by weight of each of these fatty acids was plotted versus the proportion of C10-14 fatty acids. As the proportion of C10-14 fatty acids increased from 15 to 65%, there was not a proportional decrease in the percentages of all seven fatty acids, but, instead, preferential incorporation of the essential fatty acids, AA and DHA into the triacylglycerol component of the milk. At the same time, the proportions of stearic and oleic acid declined by 69% and 86%, respectively. However, the proportions of linoleic acid, palmitic acid, DHA, AA and alpha-linolenic acid, in milk lipids decreased by only 44%, 40%, 39%, 28% and 2.3%, respectively. These observations indicate that as the contribution of C10-14 fatty acids increases, essential fatty acids are preferentially incorporated into milk triacylglycerols at the expense of oleic acid and stearic acid.     

Tissue fatty acid deposition is influenced by an interaction of dietary oil source and energy intake level in rats

To investigate the net tissue fatty acid deposition in response to graded levels of energy restriction and modification of diet fatty acid composition, rats were randomly assigned into four dietary groups and fed for 10 weeks diets containing 40% as energy of either fish, safflower, or olive oil, or beef tallow, consumed ad libitum or energy restricted to 85% or 68% of ad libitum intake by reducing diet carbohydrate content. An additional eight rats were killed before the diet regimen, to provide baseline data from which fatty acid deposition rates were calculated. Body weight, and heart, liver and fat mass gains were decreased with energy restriction (P<0.001). Olive oil feeding resulted in higher body weight gain (P < 0.03) than tallow feeding, whereas fish oil feeding was associated with highest (P < 0.007) liver weight and lowest (P < 0.03) fat mass gains. Energy deficit-related differences in the deposition of stearic, linoleic, arachidonic, and docosahexaenoic acids in heart and palmitic and docosahexaenoic acids in liver were dependent on the dietary oil consumed (P < 0.03). Similarly, interactive effects of restricted food intake and dietary oil type were found in the gain of palmitic, stearic, oleic, and linoleic acids in adipose tissue (P < 0.01) when expressed in relation to the amount of each fatty acid consumed. These data suggest that energy intake level can influence the deposition pattern, as well as oxidation rate, of tissue fatty acids as a function of tissue type, fatty acid structure, and dietary fatty acid composition.     

Inhibitory effect of fatty acids on the binding of androgen receptor and R1881

Unsaturated long chain fatty acids are known to inhibit the binding between estrogen and estrogen receptor, or progesterone and progesterone receptor in rat uterus. The effects of long chain fatty acids on the binding between androgen receptor of castrated rat prostate and 3H-R1881 were studied. The binding was not affected by saturated fatty acids such as palmitic acid (16:0) or stearic acid (18:0). But unsaturated fatty acids such as oleic acid (18:1), arachidonic acid (20:4) and docosahexaenoic acid (22:6) inhibited the binding between androgen receptor and 3H-R1881. The inhibitory effect of arachidonic acid was dose dependent. Scatchard analysis showed that the addition of arachidonic acid markedly decrease the number of binding sites of androgen receptor. But the dissociation constant was not affected. The inhibitory effect of arachidonic was not a competitive one.     

Inhibition of the binding of R-5020 and rat uterine progesterone receptors by long chain fatty acids

Long chain fatty acids were known to interfere with the binding between rat uterine estrogen receptors and estradiol. The effect of long chain fatty acids on the binding between rat progesterone receptors and 3H-R5020 was studied. The binding was inhibited by palmitic acid, palmitooleic acid, arachidonic acid and docosahexaenoic acid. Docosahexaenoic acid was the strongest inhibitor and palmitic acid was the weakest inhibitor. The inhibitory effect of palmitic acid and arachidonic acid was dose dependent. In rat uterine cytosols, there existed an arachidonic acid binding factor which was distinct from progesterone receptor. The inhibitory mechanisms of long chain fatty acids was not clear, but the inhibitory effect was stronger if the number of carbon atoms increased with the number of double bonds.     

Effects of linoleic acid and mitogenic stimulation on the fatty acid composition of human lymphocytes

Perturbation of the fatty acid composition of human lymphocytes in vitro was investigated by addition of linoleic acid complexed to bovine serum albumin (BSA-LA) and by mitogenic stimulation with phytohaemagglutinin (PHA). BSA-LA resulted in a 45% increase in linoleic acid in phosphatidylethanolamine (PE) and over 100% in phosphatidylcholine (PC) in peripheral blood cells. Supplementation with BSA-LA in PHA-stimulated lymphocytes produced even greater changes: 100% increase in linoleic acid content for PE and over 300% for PC. There was a large decrease in oleic acid: 40% for PE and almost 100% in PC. Significant decreases in arachidonic acid occurred in both phospholipid fractions. PHA alone also altered membrane phospholipid fatty acid composition, with reductions in palmitic, stearic and linoleic acid for PE and increases in oleic acid and arachidonic acid (almost 100%). For PC, there were large decreases in stearic (40%), linoleic (30%) and arachidonic (40%) acids, together with an increase in oleic acid (65%). Cells supplemented with linoleic acid grown in the presence of PHA, compared with those grown in linoleic acid-supplemented medium alone, showed a 40% decrease in palmitic acid and a 55% increase in arachidonic acid in PE. For PC, there were large decreases in stearic acid (40%) and arachidonic acid (57%). Antibody-induced redistribution of surface molecules ('capping') was inhibited by some 14% after incubation with BSA-LA. However, no consistent alterations in PHA-induced cell proliferation were observed. These data suggest that profound alterations of membrane fatty acid composition occur spontaneously during the mitotic cycle, and may be further induced by experimental manipulation, without gross perturbation of cell function.     

Long-chain acyl CoA synthetase in microsomes from rat brain gray matter and white matter

Long-chain acyl coenzyme A (CoA) synthetase in homogenates and microsomes from rat brain gray and white matter was studied. The formation of the thioesters of CoA was studied upon addition of [1-¹⁴C]-labeled fatty acids. The maximal activities were seen with linoleic acid, followed by arachidonic, palmitic, and docosahexaenoic acids in both gray and white matter homogenates and microsomes. The specific activities in microsomes were 3–5 times higher than in homogenates. The presence of Triton X-100 in the assay system enhanced the activity of long-chain acyl CoA synthetase in homogenates. The effect was more pronounced in palmitic and docosahexaenoic acid activation. The apparentK _m values andV _max values for palmitic and docosahexaenoic acids were much lower than for linoleic and arachidonic acids. The presence of Triton X-100 in the medium caused a definite decrease in the apparentK _m and Vmax values for all the fatty acid except palmitic acid in which case the reverse was true. There were no significant differences observed in the kinetic measurements between gray and white matter microsomes. These findings are similar to those resulting from the known interference of Triton X-100 in the measurement of kinetic variables of long-chain acyl CoA synthetase of liver microsomes. In this work, no correlation was observed between the fatty acid composition of gray and white matter and the capacity of these tissues for the activation of different fatty acids.     

Influence of dietary source of docosahexaenoic and arachidonic acids on their incorporation into membrane phospholipids of red blood cells in term infants

Here we studied whether the chemical structure of dietary arachidonic and docosahexaenoic acids in full-term infant diets affects their incorporation into erythrocyte membrane phospholipids. From birth to 3 months, infants were fed breast milk (n = 9) or formula milk containing arachidonic acid and docosahexaenoic acid provided by egg phospholipids (n = 10) or by low-eicosapentaenoic acid fish oil and fungal triglycerides (n = 10). We compared the fatty acid composition of erythrocyte phosphatidylethanolamine, phosphatidylcholine and sphingomyelin before and after administration of the experimental diet. At 3 months, infants on formula milk showed lower concentrations of docosahexaenoic acid (in phosphatidylcholine and in phosphatidylethanolamine) and arachidonic acid (in phosphatidylcholine) than those receiving breast milk. We conclude the incorporation of the two fatty acids into erythrocyte phospholipids depends mainly on the lipid composition of the diet received rather than the chemical form in which they are delivered.     

Changes in the higher fatty acid composition of blood plasma and erythrocyte membranes during long exposure of a human to hyperbaric gas medium

The gas chromatographic method was used to study the changes in the fatty acid composition of the sum of the blood serum and erythrocyte membrane lipids in healthy male volunteers under the conditions of simulation in the ground-based hyperbaric set of long dives at depths of up to 350 m in the oxygen-helium and oxygen-neon media and in the readaptation period. At a depth of 100 m, a decrease in the serum content of the sum of saturated acids (palmitic (16:0)n and stearic (18:0) acids) and a 1.5-fold increase in the linoleic acid content compared to the background was found. A comparison of the individual changes in the blood serum and erythrocyte membrane fatty acids, as well as the unsaturation index (UI, the ratio of the sum of the unsaturated fatty acid concentrations multiplied by the number of double bonds in the molecule to the sum of the saturated fatty acid concentrations) and the R index (the erythrocyte to the serum fatty acid content ratio), showed that, under the experimental conditions and in the period of readaptation, the main changes occurred in the erythrocyte membranes, in which the unsaturated fatty acid content increased, and the linoleic and, especially, the arachidonic acid contents changed in different directions, depending on the depth of the dive. In the readaptation period, the linoleic and arachidonic acid contents decreased twofold on the first day and exceeded even the background level on the fourth day. The data obtained give evidence for the adaptive role of the erythrocyte membrane lipids upon exposure of humans to a hyperbaric medium with a changed gas composition.     

Albumin and fatty acid effects on the stimulated production of 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) by human polymorphonuclear leukocytes.

Production of platelet-activating factor (PAF) during opsonized zymosan stimulation of human polymorphonuclear leukocytes is dependent on the concentration of extracellular albumin and on the presence of exogenous fatty acids. Fatty acid-free albumin caused a concentration-dependent increase in PAF synthesis up to 5% albumin concentrations (w/v) where the amount of PAF produced was three- to four-fold higher than in controls containing no albumin. The addition of free fatty acids, particularly arachidonic acid and palmitic acid, to 5% fatty acid-free albumin media caused a concentration-dependent decrease in PAF synthesis. A 50% inhibition of PAF synthesis was observed at an arachidonic acid concentration of 120 microM and at a palmitic acid concentration of 100 microM. The inhibition of PAF production by palmitic acid was also dependent on the concentration of extracellular albumin. In 0.5% fatty acid-free albumin media, a palmitic acid concentration of 40 microM produced a 50% inhibition in PAF synthesis. The addition of palmitic acid did not affect the release of endogenous arachidonic acid during stimulation. In contrast, the addition of stearic acid up to 120 microM in 5% fatty acid-free albumin media had no effect on PAF production. The different inhibitory effects of palmitic acid and stearic acid on PAF production may be related to differences in intracellular utilization of these two fatty acids during cell stimulation.     

Comparative levels of arachidonic acid and eicosapentaenoic acid in Malaysian fish

Total lipids were extracted from 22 species of Malaysian fish and the constituent fatty acids were analysed by gas chromatography. Malaysian fish generally contained high levels of saturated fatty acids (range 36-55% total fatty acids) and contained variable amounts of monounsaturates, chiefly palmitic and stearic acids, but only trace levels of 20:1 and 22:1. Unlike fish caught in colder northern hemisphere waters, Malaysian fish were found to contain arachidonic acid (20:4 omega 6, range 2-12%) in addition to the expected eicosapentaenoic acid (20:5 omega 3, range 1-13%) and docosahexaenoic acid (22:6 omega 3, range 6.6-40.4%).     

Gestational hyperlipidemia in the rat is characterized by accumulation of n - 6 and n - 3 fatty acids, especially docosahexaenoic acid.

We have evaluated the relative and quantitative changes in long-chain fatty acids in maternal liver, serum, carcass and conceptus (fetuses plus placentae) during pregnancy in the rat, to ascertain whether previous concern over lower proportions of n - 6 and n - 3 fatty acids in maternal serum could be indicative of suboptimal n - 6 or n - 3 fatty acid status. Gestational hyperlipidemia was characterized by proportional decreases in linoleic, stearic and arachidonic acids but increases in palmitic and docosahexaenoic acids. However, the quantitative amount (microgram/ml) of linoleic, arachidonic and docosahexaenoic acids in serum lipids actually increased 2-5-fold from mid-pregnancy to term. Compared to non-pregnant rats, gestational hyperlipidemia was also associated with a lower proportion but similar quantity of linoleic acid in maternal carcass and adipose stores. We conclude that gestational hyperlipidemia in the rat is characterized by a relative but not quantitative decrease in whole-body stores of n - 6 fatty acids and a marked proportional and quantitative increase in docosahexaenoic acid in maternal organs and in the conceptus.     

Effect of n-3 and n-6 polyunsaturated fatty acids on lymphocyte proliferation, interleukin production and phospholipid fatty acids composition in type 2 diabetic and healthy subjects in Jordan people

Dietary lipid manipulation may affect a great number of immune parameters, such as lymphocyte proliferation, cytokine synthesis. In this study, lymphocytes of diabetic type 2 were incubated with different polyunsaturated fatty acid (docosahexaenoic, eicosapentaenoic, arachidonic acid) for investigated their effect on lymphoproliferation response, the concentration of interleukin 2 produced in each essay and phospholipid fatty acid composition of lymphocyte membrane. Our results found that the concanavalin A and insulin increase significantly the proliferative response while eicosapentaenoic, arachidonic and docosahexaenoic acid inhibited that by different degrees: 47%, 37% and 19%, respectively, for healthy subjects and 39%, 29% and 13% for diabetes. However, the concentration of IL-2 produced in presence of either docosahexaenoic, eicosapentaenoic or arachidonic acid was significantly reduced by 36%, 32% and 39%, respectively, in controls while 16%, 15% and 23%, respectively, in diabetics. On the other hand, the tested fatty acids demonstrated a major impact on the fatty acid composition of different phospholipid fractions of lymphocyte membrane but these fractions were different in their response to each fatty acid examined. For instance, the addition of docosahexaenoic acid to culture media was accompanied with a predominant composition of docosahexaenoic acid in phospholipid fractions. Also, our results showed a notable increased proportion of arachidonic, eicosapentaenoic and docosahexaenoic acids in control phospholipid fractions than those of diabetic.     

Stimulation of Free Fatty Acid and Diacylglycerol Accumulation in Cerebrum and Cerebellum During Bicuculline-Induced Status Epilepticus. Effect of Pretreatment with α-Methyl-p-Tyrosine and p-Chlorophenylalanine

The pool size and composition of free fatty acids (FFA) and diglycerides (DG) from the cerebrum and cerebellum of rats undergoing bicuculline-induced seizures were studied. A fourfold increase in cerebral FFA occurred 3-4 min after bicuculline injection; arachidonic and stearic acids were the principal fatty acids accumulated. Cerebellar FFA also increased, but to a lesser extent. An increased production of arachidonic acid took place in the cerebrum as a function of time after bicuculline injection. Other fatty acids produced were oleic, palmitic, and docosahexaenoic acids. A twofold increase in cerebral arachidonic acid was seen at the time of the first generalized tonic-clonic convulsion. However, a 13- to 17-fold increase in arachidonic acid was seen approximately 5-6 min after bicuculline injection. The rise in other FFA was much smaller. Stearoyl- and arachidonoyl-DG were also accumulated. The drug alpha-methyl-p-tyrosine was found to (a) potentiate the bicuculline-stimulated release of cerebellar FFA, and (b) inhibit by 70% the production of stearoyl- and arachidonoyl-DG in the cerebrum and cerebellum. Basal production of FFA was stimulated by p-chlorophenylalanine, but the drug had no effect on the bicuculline-induced changes. Hydrolysis of phospholipids enriched in stearoyl-arachidonoyl groups, such as phosphatidylinositol of excitable membranes, may be stimulated during seizures.     

Plasma and cellular zinc levels and membrane lipid composition in streptozotocin diabetic rats

1. Lipid and zinc analyses were conducted on liver mitochondrial and microsomal membranes as well as erythrocyte ghosts from streptozotocin (STZ) treated animals. 2. In STZ animals, analysis of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) fatty acids revealed an increase in palmitic acid and a corresponding decrease in stearic acid. 3. Polyunsaturated fatty acids were also affected, with an increase in 18:2, decrease in 20:4 and an increase in 22:6 in STZ animals compared to controls. 4. The change in fatty acid composition was observed in all three membrane fractions. 5. Plasma zinc levels in STZ animals were elevated while no difference was observed in membrane bound zinc. 6. Thus, while there appears to be both altered trace metal as well as membrane lipid metabolism in STZ treated animals, membrane bound zinc does not seem to be affected.     

Further studies on the lipid metabolism of the normal and vitamin B12-deficient chick embryo

1. The triglyceride, cholesterol ester and total phospholipid fractions were isolated from the livers and yolk sacs of normal and vitamin B₁₂-deficient chick embryos after 13, 15, 17, 19 and 21 days of incubation, and the fatty acid compositions were determined. 2. At all stages of incubation, the concentration of cholesterol ester in the livers of the normal embryos were greater, and on days 15 and 17 the concentrations of triglyceride were considerably less, than the corresponding concentrations in the livers of the deficient embryos. 3. Between day 13 and day 21 of incubation the concentration of oleic acid in the liver triglycerides of the normal embryos increased, whereas the concentrations of palmitic acid and docosahexaenoic acid decreased. Vitamin B₁₂ deficiency resulted in higher concentrations of palmitic acid in the liver triglycerides on days 15, 17 and 19, higher concentrations of C₁₈ polyunsaturated acids on days 13 and 15 and lower concentrations of oleic acid on days 13, 15, 17 and 19. 4. At all stages of development, cholesterol oleate accounted for almost 80% of the total liver cholesterol esters in both normal and deficient embryos. 5. As development of the normal embryos progressed, the concentrations of palmitic acid and arachidonic acid in the liver phospholipid decreased, whereas the concentrations of stearic acid and docosahexaenoic acid increased. Vitamin B₁₂ deficiency resulted in markedly higher concentrations of stearic acid and palmitic acid and markedly lower concentrations of arachidonic acid and docosahexaenoic acid in the liver phospholipids. 6. Vitamin B₁₂ deficiency did not influence the fatty acid composition of the triglyceride, cholesterol ester and phospholipid fractions either in the yolks of fertile unincubated eggs or in the yolks obtained from eggs that had been incubated for 13, 15, 17, 19 and 21 days.     

Alterations in erythrocyte membrane lipids in abetalipoproteinemia: phospholipid and fatty acyl composition

Scanning electron microscopic observation revealed that there were wide variations including typical acanthocytes in morphology of erythrocytes from a patient with abetalipoproteinemia. The erythrocyte membrane phospholipids and cholesterol contents from a patient was higher by 25% compared to an age-matched control subject. Analysis of phospholipid composition of red blood cells showed an increase of sphingomyelin (25.1----30.1%) with a concomitant decrease of lecithin (27.5----21.0%). Thus, the sphingomyelin/lecithin ratio was increased dramatically (0.91----1.43). As for fatty acyl chain composition of main phospholipids, an increased percentage of palmitic acid and docosahexaenoic acid and a decreased proportion of arachidonic acid and lignoceric acid were observed for sphingomyelin. There was an increment of palmitic acid which was accompanied with a decrease of linoleic acid in lecithin. On the other hand, no significant difference was shown in the fatty acid composition of phosphatidylethanolamine and phosphatidylserine plus phosphatidylinositol between a patient and control.     

Eicosapentaenoic acid utilization by bovine aortic endothelial cells: effects on prostacyclin production

We have investigated whether the presence of other fatty acids in physiologic amounts will influence the effects of eicosapentaenoic acid on cellular lipid metabolism and prostaglandin production. Eicosapentaenoic acid uptake by cultured bovine aortic endothelial cells was time and concentration dependent. At concentrations between 1 and 25 microM, most of the eicosapentaenoic acid was incorporated into phospholipids and of this, 60-90% was present in choline phosphoglycerides. Eicosapentaenoic acid inhibited arachidonic acid uptake and conversion to prostacyclin (prostaglandin I2) but was not itself converted to eicosanoids. Only small effects on the uptake of 10 microM eicosapentaenoic acid occurred when palmitic, stearic or oleic acids were added to the medium in concentrations up to 75 microM. In contrast, eicosapentaenoic acid uptake was reduced considerably by the presence of linoleic, n-6 eicosatrienoic, arachidonic or docosahexaenoic acids. Although a 100 microM mixture of palmitic, stearic, oleic and linoleic acid (25:10:50:15) had little effect on the uptake of 10 or 20 microM eicosapentaenoic acid, less of this acid was channeled into endothelial phospholipids. However, the fatty acid mixture did not prevent the inhibitory effect of eicosapentaenoic acid on prostaglandin I2 formation in response to either arachidonic acid or ionophore A23187. An 8 h exposure to eicosapentaenoic acid was required for the inhibition to become appreciable and, after 16 h, prostaglandin I2 production was reduced by as much as 60%. These findings indicate that the capacity of aortic endothelial cells to produce prostaglandin I2 is decreased by continuous exposure to eicosapentaenoic acid. Even if the eicosapentaenoic acid is present as a small percentage of a physiologic fatty acid mixture, it is still readily incorporated into endothelial phospholipids and retains its inhibitory effect against endothelial prostaglandin I2 formation. Therefore, these actions may be representative of the in vivo effects of eicosapentaenoic acid on the endothelium.