Emken E A, Adlof R O, Duval S M, Nelson G J
USDA, ARS, NCAUR, Food Quality and Safety Research, Peoria, Illinois 61604, USA.
Lipids. 1997 Apr;32(4):441-8. doi: 10.1007/s11745-997-0058-4.
This study investigated the influence of dietary arachidonic acid (20:4n-6) on delta 5 desaturation and incorporation of deuterium-labeled 8cis,11 cis, 14-eicosatrienoic acid (20:3n-6) into human plasma lipids. Adult male subjects (n = 4) were fed diets containing either 1.7 g/d (HI20:4 diet) or 0.21 g/d (LO20:4 diet) of arachidonic acid for 50 d and then dosed with a mixture containing ethyl esters of 20:3n-6[d4] and 18:1n-9[d2]. A series of blood samples was sequentially drawn over a 72-h period, and methyl esters of plasma total lipid, triacylglycerol, phospholipids, and cholesteryl ester were analyzed by gas chromatography-mass spectrometry. Based on the concentration of 20:3n6[d4] in total plasma lipid, the estimated conversion of 20:3n-6[d4] to 20:4n-6[d4] was 17.7 +/- 0.79% (HI20:4 diet) and 2.13 +/- 1.44% (LO20:4 diet). The concentrations of 20:4n-6[d4] in total plasma lipids from subjects fed the HI20:4 and LO20:4 diets were 2.10 +/- 0.6 and 0.29 +/- 0.2 mumole/mL plasma/mmole of 20:3n-6[d4] fed/kg of body weight. These data indicate that conversion of 20:3n-6[d4] to 20:4n-6[d4] was stimulated 7-8-fold by the HI20:4 diet. Phospholipid acyltransferase was 2.5-fold more selective for 20:3n-6[d4] than 18:1n-9[d2], and lecithin:cholesterol acyltransferase was 2-fold more selective for 18:1n-9[ds] than 20:3n-6[d4]. These differences in selectivity were not significantly influenced by diet. Absorption of ethyl 20:3n-6[d4] was about 33% less than ethyl 18:1n-9[d2]. The sum of the n-6 retroconversion products from 20:3n-6[d4] in total plasma lipids was about 2% of the total deuterated fatty acids. Neither absorption nor retroconversion appears to be influenced by diet.
本研究调查了膳食花生四烯酸（20:4n-6）对δ5去饱和作用以及氘标记的8顺式、11顺式、14-二十碳三烯酸（20:3n-6）掺入人血浆脂质的影响。成年男性受试者（n = 4）分别摄入含1.7 g/d（高20:4饮食）或0.21 g/d（低20:4饮食）花生四烯酸的饮食50天，然后给予含20:3n-6[d4]和18:1n-9[d2]乙酯的混合物。在72小时内依次采集一系列血样，通过气相色谱-质谱法分析血浆总脂质、三酰甘油、磷脂和胆固醇酯的甲酯。根据总血浆脂质中20:3n6[d4]的浓度，估计20:3n-6[d4]向20:4n-6[d4]的转化率在高20:4饮食组为17.7±0.79%，在低20:4饮食组为2.13±1.44%。高20:4饮食组和低20:4饮食组受试者总血浆脂质中20:4n-6[d4]的浓度分别为2.10±0.6和0.29±0.2微摩尔/毫升血浆/每千克体重摄入的20:3n-6[d4]毫摩尔。这些数据表明，高20:4饮食使20:3n-6[d4]向20:4n-6[d4]的转化率提高了7 - 8倍。磷脂酰转移酶对20:3n-6[d4]的选择性比对18:1n-9[d2]高2.5倍，卵磷脂胆固醇酰基转移酶对18:1n-9[ds]的选择性比对20:3n-6[d4]高2倍。这些选择性差异未受饮食的显著影响。20:3n-6[d4]乙酯的吸收率比18:1n-9[d2]乙酯低约33%。总血浆脂质中20:3n-6[d4]的n-6逆向转化产物之和约占总氘代脂肪酸的2%。吸收率和逆向转化似乎均不受饮食影响。
