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PubMed1999

Fatty acid composition of caprine milk: major, branched-chain, and trans fatty acids.

The fatty acid composition of caprine milk fat was studied using capillary gas chromatography. Milk was obtained from five goat herds belonging to different breeders in the Murcia region (Spain) and collected monthly (from November to May). The results showed significant differences among herds mainly in long-chain fatty acids (C16:0, C18:0, and C18:2). There were five branched-chain fatty acids (iso- and anteiso-C15:0, iso- and anteiso-C17:0, and iso-C16:0) with > 0.1% of the total fatty acid methyl esters and another 31 (the most monomethylated) with < 0.1%, including 4-ethyloctanoate, which is implicated in goat-like flavors. To study the content of trans unsaturated fatty acids, the fatty acid methyl esters were previously fractionated by AgNO3-thin layer chromatography. The mean contents of trans-C16:1 and trans-C18:1 were 0.16 and 2.12%, respectively. The distribution profile of trans-C18:1 was also studied.

Animals↗
PubMed2000

Cloning and functional expression of the first plant fatty acid elongase specific for Delta(6)-polyunsaturated fatty acids.

In order to elucidate the biosynthesis of long-chain polyunsaturated fatty acids (PUFAs) in plants we searched for a cDNA encoding a Delta(6)-specific PUFA elongase from Physcomitrella patens, which is known to contain high proportions of arachidonic acid (20:4 Delta(5,8,11,14)). An EST clone from P. patens was identified by its low homology to the yeast gene ELO1, which is required for the elongation of medium-chain fatty acids. We functionally characterized this cDNA by heterologous expression in Saccharomyces cerevisiae grown in the presence of several fatty acids. Analysis of the fatty acid profile of the transgenic yeast revealed that the cDNA encodes a protein that leads to the elongation of the C(18) Delta(6)-polyunsaturated fatty acids gamma-linolenic acid (18:3 Delta(6,9,12)) and stearidonic acid (18:4 Delta(6,9,12,15)), which were recovered to 45-51% as their elongation products. In contrast, linoleic and alpha-linolenic acids were hardly elongated and we could not measure any elongation of saturated and mono-unsaturated fatty acids (including 18:1 Delta(6)), indicating that the elongase is highly specific for the polyunsaturated nature of the fatty acid acting as substrate.

Acetyltransferases↗
PubMed1979

Intensification of essential fatty acid deficiency in the rat by dietary trans fatty acids.

Two studies were conducted using male rats to assess the effect of trans fatty acids upon essential fatty acid (EFA) deficiency. In the first study 5% corn oil (CO), hydrogenated coconut oil (HCNO) or margarine stock (MS, partially hydrogenated soybean oil) were fed, and the levels of trans fatty acids in tissue lipids were measured. The trans fatty acids present in MS were found to intensify EFA deficiency and to be retained in tissue lipids to a high degree, especially in heart phospholipids (PL). In the second study, as the level of trans fatty acids increased in the diet, increasingly higher levels of trans fatty acids were deposited in the heart PL. As dietary trans acid increased, a decrease in total omega 6 fatty acids, and a decrease in the sum of 18:2 omega 6 + 20:4 omega 6 - 20:3 omega 9 fatty acids in heart PL occurred, both criteria indicating a shift toward an increasing EFA deficiency state. Studies of delta 5 desaturase activity of liver microsomes in selected groups showed an increase in the conversion of 20:3 omega 6 to 20:4 omega 6 as the trans fatty acid level in the diet increased.

Animals↗
PubMed2001

Developmental variation of sugars, carboxylic acids, purine alkaloids, fatty acids, and endoproteinase activity during maturation of Theobroma cacao L. seeds.

The changes of mono- and oligosaccharides, carboxylic acids, purine alkaloids, and fatty acid composition, and of aspartic endoproteinase activity, were analyzed during seed development in two varieties of cacao (Theobroma cacao). The majority of the components examined either decreased or accumulated steadily in concentration during the second half of bean development. Sucrose is the major sugar in the mature embryo, whereas fructose and glucose are at higher concentrations in the endosperm tissue. Considerable amounts of malate are found in the endosperm, whereas citrate is the dominant carboxylic acid in the embryo. A major change in the fatty acid composition occurs in the young embryo when the proportion of stearic acid increases rapidly at the expense of linoleic acid, which is reduced from about 18 to 3%. Theobromine is the dominant purine alkaloid (ca. 80%), and caffeine appears only toward the end of seed maturity. Aspartic endoproteinase activity increases rapidly during embryo expansion, reaching a maximal activity before final maturity. The results are discussed in conjunction with physiological changes in developing seeds, and the potential contributions of the compounds analyzed for cocoa quality.

Aspartic Acid Endopeptidases↗
PubMed2000

Incorporation and metabolism of dietary trans isomers of linolenic acid alter the fatty acid profile of rat tissues.

To study the influence on lipid metabolism and platelet aggregation of the fatty acid isomerization that occurs during heat treatment, weanling rats were fed for 8 wk a diet enriched with 5% isomerized (experimental group) or normal (control group) canola oil. Geometrical isomers of alpha-linolenic acid representing 0.2 g/100 g of the experimental diet were incorporated into liver, platelets, aorta and heart, at the expense of their cis homologue and of 18:2(n-6). The major isomer, 9c,12c,15t-18:3, was also metabolized to 5c,8c,11c,14c,17t-20:5 and to an unknown compound, found in liver, platelets and aorta, which has been identified tentatively as 7c, 10c,13c,16c,19t-22:5. The greater 20:4(n-6)/18:2(n-6) ratio in the liver, platelets and heart of the experimental group than the control group indicated an enhancement of desaturation activities. This induced a higher content of long-chain (n-6) fatty acids in the experimental group. Platelet aggregation tended to be slightly higher (P: = 0.065) in the experimental group. We conclude that 0.2 g of trans isomers of alpha-linolenic acid per 100 g of diet was sufficient to be incorporated and metabolized, thus altering the fatty acid profile of rat tissues.

Animals↗
PubMed1986

The influence of dietary manipulation with n-3 and n-6 fatty acids on liver and plasma phospholipid fatty acids in rats.

The interrelations between linoleic acid (LA) metabolites and fish oil fatty acids were studied. Sprague-Dawley rats (200-220 g) were fed a fat-free semisynthetic diet supplemented with 10% (by weight) of different combinations of evening primrose oil (EPO), a rich source of LA and gamma-linolenic acid, and polepa (POL), a marine oil rich in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The combinations of supplement were as follows: 9% EPO-1% POL, 8% EPO-2% POL, 7% EPO-3% POL, 6% EPO-4% POL and 5% EPO-5% POL. After two weeks on the respective diets, the animals were killed, and the fatty acid compositions of liver and plasma phospholipids were examined. The results showed that animals fed higher proportions of POL consistently contained higher levels of dihomo-gamma-linolenic acid (DGLA) (p less than 0.05), a metabolite of LA and GLA, and lower levels of arachidonic acid (AA) (p less than 0.01), a metabolite of DGLA through delta-5-desaturation. Thus, an inverse relationship between AA/DGLA ratio and EPA levels was found to exist (r = -0.765 in plasma and -0.792 in liver). However, there was no such relationship between AA/DGLA ratio and DHA levels. This result suggested that EPA but not DHA in fish oil exerts an inhibitory effect on the conversion of DGLA to AA.

Animals↗
PubMed2000

Dietary essential fatty acids, long-chain polyunsaturated fatty acids, and visual resolution acuity in healthy fullterm infants: a systematic review.

BACKGROUND: Biologically active neural tissue is rich in docosahexaenoic acid (DHA), an omega-3 long-chain polyunsaturated fatty acid (LCPUFA). We conducted a systematic review to examine the nature of discordant results from studies designed to test the hypothesis that dietary DHA leads to better performance on visually-based tasks in healthy, fullterm infants. We also conducted a meta-analysis to derive combined estimates of behavioral- and electrophysiologic-based visual resolution acuity differences and sample sizes that would be useful in planning future research. STUDY DESIGN AND METHODS: Twelve empirical studies on LCPUFA intake during infancy and visual resolution acuity were identified through bibliographic searches, examination of monograph and review article reference lists, and written requests to researchers in the field. Works were reviewed for quality and completeness of information. Study design and conduct information was extracted with a standardized protocol. Acuity differences between groups consuming a source of DHA and groups consuming DHA-free diets were calculated as a common outcome from individual studies; this difference score was evaluated against a null value of zero and then used, with the method of DerSimonian and Laird (Meta-analysis in clinical trials. Control Clin Trials 1986;7:177-188), to derive combined estimates of visual resolution acuity differences within seven age categories. RESULTS OF RANDOMIZED COMPARISONS: The combined visual resolution acuity difference measured with behaviorally based methods between DHA-supplemented formula fed groups and DHA-free formula fed groups is 0.32+/-0.09 octaves (combined difference+/-S.E.M., P=0.0003) at 2 months of age. The direction of this value indicates higher acuity in DHA-fed groups. RESULTS OF NON-RANDOMIZED STUDY DESIGNS: The combined visual resolution acuity difference measured with behaviorally based methods between human milk fed groups and DHA-free formula fed groups is 0.49+/-0.09 octaves (P< or =0.000001) at 2 months of age and 0.18+/-0.08 octaves (P=0.04) at 4 months of age. Acuity differences for electrophysiologic-based measures are also greater than zero at 4 months (0.37+/-0.16 octaves, P=0.02). CONCLUSION: Some aspect of dietary n-3 intake is associated with performance on visual resolution acuity tasks at 2, and possibly, 4 months of age in healthy fullterm infants. Whether n-3 intake confers lasting advantage in the development of visually based processes is still in question.

Bottle Feeding↗
PubMed1992

Plasma and red blood cell fatty acid values as indexes of essential fatty acids in the developing organs of infants fed with milk or formulas.

The dietary requirement of n-6 and n-3 fatty acids for normal biochemical and functional development of the central nervous system (CNS) is an important, unresolved issue in infant nutrition. High levels of arachidonic acid (AA; 20:4n-6) and docosahexaenoic acid (DHA; 22:6n-3) are found in the CNS and are important to normal learning and visual function. Dietary fatty acids may be desaturated and elongated to AA and DHA, respectively, but may also be oxidized for energy. Synthesis of AA and DHA in the young infant, therefore, depends on adequate desaturase enzyme activity, as well as an adequate supply of dietary 18:2n-6, 18:3n-3, and energy. Levels of AA and DHA are lower in the plasma and red blood cell (RBC) lipids of infants fed formula rather than human milk and are not increased with increased formula 18:2n-6 or 18:3n-3 supply. The decline in AA and DHA in infants fed formula becomes evident in the order plasma phospholipid greater than RBC phosphatidylcholine greater than RBC phosphatidylethanolamine. As in infants, piglets fed formula rather than natural milk have lower plasma and RBC AA and DHA concentrations. Despite lower levels in the plasma and RBC, analyses of CNS lipids demonstrated adequate AA and DHA in piglets fed formula with greater than 7% kcal 18:2n-6 and greater than 0.3% kcal 18:3n-3. This finding suggests that circulating lipid fatty acids are not specific indexes of organ deficiency. The rapid decrease in circulating lipid AA and DHA concentrations experienced by premature infants during early postnatal parenteral and enteral nutrition, however, may be related to oxidation of 18:2n-6 and 18:3n-3, rather than equilibrium of circulating lipids with the dietary fatty acids. Arachidonic acid and DHA may be conditionally essential nutrients for these infants because of oxidation of 18:2n-6 and 18:3n-3 for energy during periods of negative energy balance.

Animals↗
PubMed1977

Total parenteral nutrition in infants. Blood levels of glucose, lactate, pyruvate, free fatty acids, glycerol, d-beta-hydroxybutyrate, triglycerides, free amino acids and insulin.

Two regimens (A and B) for TPN were designed to meet the requirements of newborn infants for calories, amino acids, fatty acids, electrolytes, trace elements and vitamins. Both "A" and "B" included fat emulsion (Intralipid). "A" contained fructose and glucose, "B" glucose only. "A" provided amino acids (Vamin) in proportions similar to those of whole egg, "B" similar to those of human milk. All nutrients were given simultaneously into peripheral veins by constant infusion. Nineteen patients (11 newborns, 8 infants) were studied for 1-28 days. Twelve infants recovered, 7 died. In none could TPN be regarded as the cause of death. Treatment was complicated by sepsis in 5 infants. During the course of treatment, blood levels of substrates and insulin were measured before, during and 30 min after discontinuation of TPN. Highly raised concentrations of circulating substrates seen in 3 infants seemed to be related to a poor clinical condition rather than to the regimen used. Infants in good condition tolerated TPN well. Low levels of branch-chained amino acids and tendency to ketonemia, when infusion was stopped, suggested that minimal rather than optimal supply of energy and of amino acids in relation to energy was provided with both regimens. Low insulin levels associated with elevated blood levels of substrates suggested that insulin administration to selected cases might be indicated. Fructose (0.30 g/kg X hour-1) given with regimen A increased blood lactate concentrations. Homocystinaemia appeared in 2 cases; disappearance after excess vitamin B6 administration indicated increased B6 requirement.

Amino Acids↗
PubMed1988

Analysis of fatty acids by negative ion gas chromatography/tandem mass spectrometry: structural correlations between alpha-mycolic acid chains and delta-5-monounsaturated fatty acids from Mycobacterium phlei.

The analysis of a complex mixture of monounsaturated fatty acids from mycobacterium phlei is achieved by capillary gas chromatographic separation of their pentafluorobenzyl esters, formation of gas-phase carboxylate anions by electron capture ionization and decomposition of these anions by collision activation. This method allows the structural determination of fatty acid isomers by examination of their collisionally activated dissociation mass-analysed ion kinetic energy spectra. A good correlation is observed between the structure of the unsaturated fatty acids ranging from C24 to C27 and the methyl terminal part of the main chain of diunsaturated mycolic acids.

Fatty Acids↗
PubMed1985

Jejunal uptake of sugars, cholesterol, fatty acids, and fatty alcohols in vivo in diabetic rats.

Previous in vitro studies have demonstrated enhanced active and passive intestinal uptake of nutrients in streptozotocindiabetic rats, but the effect of diabetes on the in vivo absorption of glucose and amino acids remains controversial, and the effect of diabetes on the in vivo uptake of lipids has not been reported. Accordingly, an in vivo perfusion technique was used in rats to examine the uptake of nutrients from the intestinal lumen, their transfer to the body, their mucosal and submucosal content, and the percentage of uptake transferred. Diabetes was associated with reduced uptake of fatty alcohols, indicating that the effective resistance of the unstirred water layer in vivo is higher in diabetic than in nondiabetic control rats. The mucosal and submucosal content of dodecanol was lower in diabetic than in control rats, but the percentage of the dodecanol uptake transferred to the body was higher. Although the uptake of varying concentrations of D-galactose was similar in diabetic and in control animals, kinetic analysis corrected for unstirred layer effects demonstrated lower mean values of the passive permeability coefficients (Pd) for galactose in diabetic than in control animals, with lower values of the Michaelis constant (Km) and higher values of the maximal transport rate (Jmd). The uptake of lauric acid was reduced in diabetic rats, whereas the uptake of deconoic acid and of cholesterol was unchanged. With correction for unstirred layer effects, it was apparent that the jejunum of diabetic rats was in fact more permeable to decanoic and lauric acid as well as to cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

A method for quantitative acylcarnitine profiling in human skin fibroblasts using unlabelled palmitic acid: diagnosis of fatty acid oxidation disorders and differentiation between biochemical phenotypes of MCAD deficiency.

Inherited disorders of fatty acid oxidation are a group of acute life-threatening but treatable disorders, clinically complicated by severe hypoketotic hypoglycemia precipitated by prolonged fasting. Among them, medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is by far the most frequent disorder. Here we report a modified method for quantitative acylcarnitine profiling by electrospray ionisation-tandem mass spectrometry (ESI-MS-MS) in human skin fibroblasts using unlabelled palmitic acid as substrate. The reliability of this method was tested in cultured skin fibroblasts from previously diagnosed patients with specific carnitine cycle and fatty acid beta-oxidation defects. Furthermore, acylcarnitine profiling was investigated in fibroblasts and dried blood spots from patients with different variants of MCAD deficiency. ESI-MS-MS-based investigation of cultured skin fibroblasts from patients with disorders of fatty acid oxidation revealed a pathognomonic acylcarnitine profiling. In addition, this method delineated different variants of MCAD deficiency, i.e. mild and classical. The octanoylcarnitine (C8)-to-decanoylcarnitine (C10) and C8-to-acetylcarnitine (C2) ratios were the most specific markers to differentiate mild and classical forms of MCAD deficiency in fibroblasts. Similar results were obtained by quantitative acylcarnitine profiling in dried blood spots. In conclusion, this novel technique is a powerful tool for the investigation of fatty acid oxidation disorders under standardized conditions in fibroblasts.

Acyl-CoA Dehydrogenase↗
PubMed1990

Alterations in dietary fatty acid composition alter rat brush border membrane phospholipid fatty acid composition.

Female Wistar rats were fed for 8 weeks a high polyunsaturated fatty acid diet (P) enriched with 18:2w6 and 18:3w3, or a high saturated fatty acid diet (S) enriched with 16:0, 18:0 and 18:1w9. There was a similar jejunal BBM fatty acid profile in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) composition in animals fed P. However, feeding S altered the fatty acid composition of BBM phospholipids: for PC, feeding S increased total monounsaturated fatty acids (e.g. 18:1(9)) and reduced total polyunsaturated fatty acids, especially the total w6 fatty acids. For PE, feeding S increased only the total monounsaturated fatty acids. The ratio of monounsaturated/saturated fatty acids was increased for PC and PE. Fatty acid changes were more pronounced in the jejunal than ileal BBM. It is concluded that alterations in dietary fatty acid saturation: (a) influences intestinal BBM phospholipid fatty acid composition; (b) these changes are quantitatively and qualitatively different for PC and PE; and (c) changes are greater in the proximal than in the distal intestine. It is proposed that the previously reported diet-associated changes in active and passive intestinal transport are due at least in part to these alterations in the fatty acid composition in brush border membrane phospholipids.

Animals↗
PubMed2001

Infant plasma trans, n-6, and n-3 fatty acids and conjugated linoleic acids are related to maternal plasma fatty acids, length of gestation, and birth weight and length.

BACKGROUND: Arachidonic acid (AA) and docosahexaenoic acid (DHA) are important for growth and neural development. trans Fatty acids (TFAs) may inhibit desaturation of linoleic acid (LA) and alpha-linolenic acid (ALA) to AA and DHA, respectively. Conjugated linoleic acids (CLAs) also alter lipid metabolism and body fat. OBJECTIVE: We determined the associations of birth outcome with maternal and infant plasma concentrations of TFAs, CLAs, AA, and DHA. DESIGN: In healthy women, we sampled maternal blood at 35 wk gestation (n = 58) and umbilical cord blood at birth (n = 70). RESULTS: Mean (+/- SEM) TFA concentrations (% by wt) in infant plasma were as follows: triacylglycerol, 2.83 +/- 0.19 (range: 0.63-12.79); phospholipid, 0.67 +/- 0.03 (0.11-1.33); and cholesteryl ester, 2.04 +/- 0.01 (0.86-4.24). LA, AA, DHA, TFA, and CLA concentrations in infant phospholipids correlated with the same fatty acid in maternal plasma phospholipids (n = 44; P < 0.05). Infant plasma cholesteryl ester and triacylglycerol TFAs and cholesteryl ester CLAs (r = -0.33, -0.42, and -0.49, respectively) were significantly inversely related to length of gestation. Triacylglycerol and cholesteryl ester AA were positively related to length of gestation (r = 0.41 and 0.37, respectively) and birth weight (r = 0.27 and 0.23, respectively). Inverse correlations occurred between infant plasma TFA and DHA concentrations in triacylglycerols (r = -0.33) and between TFA and AA concentrations in cholesteryl esters (r = -0.23). CONCLUSION: The results suggest possible important effects of TFAs and of AA on fetal growth and length of gestation.

Arachidonic Acid↗
PubMed2002

New insights into long-chain fatty acid uptake by heart muscle: a crucial role for fatty acid translocase/CD36.

Long-chain fatty acids are an important source of energy for several cell types, in particular for the heart muscle cell. Three different proteins, fatty acid translocase (FAT)/CD36, fatty acid transport protein and plasma membrane fatty acid binding protein, have been identified as possible membrane fatty acid transporters. Much information has been accumulated recently about the fatty acid transporting function of FAT/CD36. Several experimental models to study the influence of altered FAT/CD36 expression on fatty acid homoeostasis have been identified or developed, and underscore the importance of FAT/CD36 for adequate fatty acid transport. These models include the FAT/CD36 null mouse, the spontaneously hypertensive rat and FAT/CD36-deficient humans. The fatty acid transporting role of FAT/CD36 is further demonstrated in mice overexpressing muscle-specific FAT/CD36, and in transgenic mice generated using a genetic-rescue approach. In addition, a wealth of information has been gathered about the mechanisms that regulate FAT/CD36 gene expression and the presence of functional FAT/CD36 on the plasma membrane. Available data also indicate that FAT/CD36 may have an important role in the aetiology of cardiac disease, especially cardiac hypertrophy and diabetic cardiomyopathy. This review discusses our current knowledge of the three candidate fatty acid transporters, the metabolic consequences of alterations in FAT/CD36 levels in different models, and the mechanisms that have been identified for FAT/CD36 regulation.

Animals↗
PubMed1999

Fatty acid ethyl and methyl ester synthases, and fatty acid anilide synthase in HepG2 and AR42J cells: interrelationships and inhibition by tri-o-tolyl phosphate.

Synthesis of fatty acid ethyl esters (FAEEs), fatty acid methyl esters (FAMEs), and fatty acid anilides (FAAs) in humans and/or experimental animals and in vitro have been reported by us and other investigators. In previous studies, we have demonstrated that fatty acid ethyl ester synthase (FAEES), purified from rat liver microsomes, is structurally and functionally identical to the rat liver microsomal carboxylesterase (pI 6.1) and suggested a role in the conjugation of a variety of xenobiotic alcohols with endogenous fatty acids (B. S. Kaphalia, R. R. Fritz, and G. A. S. Ansari, Chem. Res. Toxicol. 11, 211-218, 1997). However, hepatic FAEES was found to be structurally and functionally different from that of pancreas. Therefore, the present study was undertaken to determine structural and functional interrelationships among the enzyme(s) involved in the synthesis of FAEEs, FAMEs, and FAAs, in HepG2 and AR42J cells using tri-o-tolyl phosphate (TOTP), a specific inhibitor for beta-esterases. Synthesis of FAEEs, FAMEs, and FAAs, studied in the HepG2 cells, was found to be dose- and time-dependent following incubation with methanol, ethanol, or aniline, respectively. Approximately 86-90% inhibition of FAEE, FAME, and FAA synthesizing activities was found in HepG2 cells following exposure to 2.5 microM TOTP. Identical profiles of dose- and time-dependent inhibition of FAEE, FAME, and FAA synthesizing activities by TOTP in HepG2 cells suggest that synthesis of FAEEs, FAMEs, and FAAs is catalyzed by the same enzyme(s). However, FAEE, FAME, and FAA synthesizing activities in AR42J cells could not be inhibited by TOTP under similar experimental conditions. A differential pattern of p-nitrophenyl acetate hydrolyzing activity (a measure of esterase activity) similar to that of fatty acid ester/anilide synthesizing activities was observed in the two cell lines. These results are further substantiated by the presence of approximately 60 kDa (subunit molecular weight) protein in the postnuclear fraction of HepG2 but not in AR42J cells by Western blot analysis using antibodies raised against FAEES, purified from rat liver microsomes or adipose tissue. Therefore, the enzyme responsible for the FAEE, FAME, or FAA synthesizing activities is most probably carboxylesterase in HepG2 cells and is structurally and functionally different than that present in AR42J cells. These studies also indicate the utility of HepG2 and AR42J cell cultures as an alternative to the animal model regarding studies on nonoxidative metabolism of alcohols and amines, in general.

Aniline Compounds↗
PubMed1998

A neuronal two P domain K+ channel stimulated by arachidonic acid and polyunsaturated fatty acids.

TWIK-1, TREK-1 and TASK K+ channels comprise a class of pore-forming subunits with four membrane-spanning segments and two P domains. Here we report the cloning of TRAAK, a 398 amino acid protein which is a new member of this mammalian class of K+ channels. Unlike TWIK-1, TREK-1 and TASK which are widely distributed in many different mouse tissues, TRAAK is present exclusively in brain, spinal cord and retina. Expression of TRAAK in Xenopus oocytes and COS cells induces instantaneous and non-inactivating currents that are not gated by voltage. These currents are only partially inhibited by Ba2+ at high concentrations and are insensitive to the other classical K+ channel blockers tetraethylammonium, 4-aminopyridine and Cs+. A particularly salient feature of TRAAK is that they can be stimulated by arachidonic acid (AA) and other unsaturated fatty acids but not by saturated fatty acids. These channels probably correspond to the functional class of fatty acid-stimulated K+ currents that recently were identified in native neuronal cells but have not yet been cloned. These TRAAK channels might be essential in normal physiological processes in which AA is known to play an important role, such as synaptic transmission, and also in pathophysiological processes such as brain ischemia. TRAAK channels are stimulated by the neuroprotective drug riluzole.

Amino Acid Sequence↗
PubMed1999

An optimized method for fatty acid analysis, including quantification of trans fatty acids, in human adipose tissue by gas-liquid chromatography.

Considering the need for a quick direct method for measurement of the fatty acid composition including trans isomers of human adipose tissue we have developed a procedure using gas-liquid chromatography (GLC) alone, which is thus suitable for validation of fatty acid status in epidemiological studies. Fatty acids ranging in carbon number from 12 to 22 and with 0-6 double bonds were resolved and identified by capillary column GLC with a temperature program starting at 150 degrees C. Following injection, the oven temperature was increased at a rate of 3 degrees C/min to 200 degrees C, then held constant for 25 min, and finally raised at 25 degrees C/min to 225 degrees C. The trans and cis isomers of 18:1 were well separated from each other, as shown by silver-ion thin-layer chromatography. Verification by standards showed that the trans 18:1 isomers with a double bond in position 12 or lower were separated from the cis 18:1 isomers with a double bond in position 6 or higher. As the adipose tissue samples contained only small amounts of the 13t-, 14t- and 15t-18:1 isomers and the 4c- and 5c-18:1 isomers the overlapping was found to be minimal. The GLC method may also be valuable for determining the fatty acid profiles including total trans in other tissues.

Adipose Tissue↗