[55] General procedures for separating lipid components of tissue

Entenman, C.

doi:10.1016/s0076-6879(57)03395-9

Cited by 105 publications

(41 citation statements)

References 26 publications

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“…[ 14 C]CO 2 produced by muscle was liberated from the medium as described above and quantified. After CO 2 trapping, no significant increases in 14 C over background were measured (13) in media in which muscles had been incubated, indicating little release of acid-soluble metabolites. Lipids were extracted from muscle (14), and TAG, diacylglycerol, phospholipid, and fatty acids (FA) were separated by thin-layer chromatography on scored silica gel G plates in hexane:diethyl ethenacetic acid (80:20:1; vol/vol/vol) and quantified using a Bioscan 200 system.…”

Section: Animals and Muscle Incubationsmentioning

confidence: 94%

Leptin Directly Alters Lipid Partitioning in Skeletal Muscle

et al. 1997

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Leptin, an adipocyte-derived hormone that directly regulates both adiposity and energy homeostasis, decreases food intake and appears to partition metabolic fuels toward utilization and away from storage. Because skeletal muscle expresses the leptin receptor and plays a major role in determining energy metabolism, we studied leptin's effects on glucose and fatty acid (FA) metabolism in isolated mouse soleus and extensor digitorum longus (EDL) muscles. One muscle from each animal served as a basal control. The contralateral muscle was treated with insulin (10 mU/ml), leptin (0.01-10 ug/ml), or insulin plus leptin, and incorporation of [ C]glucose or [14 C]oleate into CO 2 and into either glycogen or triacylglycerol (TAG) was determined. Leptin increased soleus muscle FA oxidation by 42% (P < 0.001) and decreased incorporation of FA into TAG by 35% (P < 0.01) in a dose-dependent manner. In contrast, insulin decreased soleus muscle FA oxidation by 40% (P < 0.001) and increased incorporation into TAG by 70% (P < 0.001). When both hormones were present, leptin attenuated both the antioxidative and the lipogenic effects of insulin by 50%. Less pronounced hormone effects were observed in EDL muscle. Leptin did not alter insulin-stimulated muscle glucose metabolism. These data demonstrate that leptin has direct and acute effects on skeletal muscle. Diabetes 46:1360-1363, 1997 H omozygous ob/ob mice lack functional leptin, a 16-kDa peptide hormone that is expressed and secreted by adipose tissue, and exhibit an obesity syndrome characterized by hyperphagia, hypothermia, hyperlipidemia, hyperinsulinemia, and insulin resistance (1). When administered to ob/ob mice, leptin reduces food intake and increases energy expenditure (2,3). Received for publication 28 March 1997 and accepted in revised form 7 May 1997.BSA, bovine serum albumin; EDL, extensor digitorum longus; FA, fatty acid; mKRB, modified Krebs-Ringer buffer; TAG, triacylglycerol.Both lean and obese animals treated with leptin lose fat mass but retain lean body mass (2,3). In ob/ob mice, leptin also normalizes serum concentrations of glucose, insulin, and lipids (2). The latter effects are observed at low leptin doses that do not affect body weight, suggesting that leptin's metabolic effects precede its effects on food intake and weight (2). In pair-feeding studies, leptin-injected mice lose 30-50% more weight and 50-100% more fat mass than pair-fed controls (4). Leptin treatment increases energy expenditure (2), whereas energy is conserved during food restriction (4,5). These data strongly suggest that leptin modulates energy homeostasis in part through mechanisms that are independent of food intake and that it directs metabolic fuels toward oxidation and away from storage.Skeletal muscle accounts for a large proportion of insulinstimulated glucose uptake and whole-body lipid oxidation and is the major tissue contributing to resting metabolic rate. Because each of these factors is affected by leptin in ob/ob mice (2-4) and because skeletal muscle expresses both lo...

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Section: Animals and Muscle Incubationsmentioning

confidence: 94%

Leptin Directly Alters Lipid Partitioning in Skeletal Muscle

et al. 1997

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“…A subgroup of 27 fish-fed and 24 beef-fed animals in group 2 were bled via the retro-orbital venous sinus every 2 mo, beginning at 4 mo ofage, for analysis of anti-double-stranded DNA antibodies by a modified Farr technique, as described (11), and for fatty acid analysis. 100 ,ul of sera from four animals in each dietary group, obtained at 8 mo of age, was extracted using an ethanol:ether procedure as described (12). 10 ,ul-samples of the melted beef tallow and menhaden oil were also subjected to analysis.…”

Section: Methodsmentioning

confidence: 99%

Dietary enrichment with the polyunsaturated fatty acid eicosapentaenoic acid prevents proteinuria and prolongs survival in NZB x NZW F1 mice.

Prickett¹,

Robinson²,

Steinberg³

1981

J. Clin. Invest.

308

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“…Fatty acid analysis. Diets, tumor tissue or liver, were extracted using an ethanol/ether procedure (23). Methyl esters of the extracted samples were prepared using a 16-h incubation at 650C with 0.5 N methanolic HCl.…”

Section: Methodsmentioning

confidence: 99%

Dietary menhaden oil lowers plasma prostaglandins and calcium in mice bearing the prostaglandin-producing HSDM1 fibrosarcoma.

Tashjian¹,

Voelkel²,

Robinson³

et al. 1984

J. Clin. Invest.

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A bstract. The w3 class of polyunsaturated fatty acids, particularly eicosapentaenoic acid (EPA, 20:5), has been shown to alter the patterns of arachidonic acid (20:4) metabolism, in both in vitro and in vivo systems. To examine further the role of arachidonic acid conversion to prostaglandins (PG) contents of PGE2, PGF2a, and 6-keto-PGF,,, were lower in tumor tissue from animals eating the diet high in EPA, whereas the tissue contents of i 12-HETE and iSRS were not altered by diet. Fatty acid analysis of liver and tumor tissue revealed marked increases in certain w3 fatty acids (20:5, 22:5, and 22:6)

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[55] General procedures for separating lipid components of tissue

Cited by 105 publications

References 26 publications

Leptin Directly Alters Lipid Partitioning in Skeletal Muscle

Leptin Directly Alters Lipid Partitioning in Skeletal Muscle

Dietary enrichment with the polyunsaturated fatty acid eicosapentaenoic acid prevents proteinuria and prolongs survival in NZB x NZW F1 mice.

Dietary menhaden oil lowers plasma prostaglandins and calcium in mice bearing the prostaglandin-producing HSDM1 fibrosarcoma.

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