Vermunt S H, Mensink R P, Simonis M M, Wagenmakers A J, Hornstra G
Department of Human Biology, Maastricht University, Maastricht, The Netherlands.
Eur J Clin Nutr. 2001 May;55(5):321-6. doi: 10.1038/sj.ejcn.1601158.
To investigate the in vivo oxidation of (13)C18:2n-6 and its conversion into longer-chain polyunsaturates (LCPs) in healthy subjects.
Blood samples were collected from six subjects before (fasted) and 7, 11 (non-fasted), 24, 48, 72, 168 and 336 h (fasted) after ingestion of a single bolus of 45 mg uniformly labeled (13)C18:2n-6 dissolved in 8 g olive oil. In three subjects, breath was also sampled and CO(2) production measured every hour during the first 12 h. Subjects consumed their habitual diets. Plasma (13)C-enrichments were measured by GC-C-IRMS and fatty acid compositions by GC/FID.
Maastricht University, Department of Human Biology.
Three men and three women, recruited by local advertisement.
The tracer/tracee ratio (TTR) of C18:2n-6 in plasma total lipids was already increased 5 h after tracer intake. The mean peak amount (+/-s.e.m) of (13)C18:2n-6 (3.4+/-0.8 mg; 7.6% of dose) was found after about 17 h, (13)C18:3n-6 (0.018+/-0.008 mg; 0.04% of dose) after 7-48 h, and (13)C20:3n-6 (0.028+/-0.011 mg; 0.06% of dose) after 48-336 h. Time to peak TTRs of C20:4n-6 varied between subjects and were on average 0.022+/-0.006 mg (0.05% of dose). The proportion of (13)C18:2n-6 recovered in breath after 12 h ranged between 16.8 and 25.1%.
These findings suggest that a single bolus of 45 mg U-(13)C18:2n-6 can be used to study the oxidation of (13)C18:2n-6. However, because of the low TTRs for C20:4n-6, a higher dose is recommended for studying the conversion of (13)C18:2n-6 into LCPs. In addition, since only about 35% of the tracer was found in plasma total lipids and as (13)CO(2) in breath, it might be necessary to study other accessible lipid fractions as well to study the overall conversion of linoleic acid.
研究健康受试者体内(13)C18:2n-6的氧化及其向长链多不饱和脂肪酸（LCPs）的转化。
从6名受试者中采集血样，在摄入单次大剂量45 mg均匀标记的(13)C18:2n-6（溶于8 g橄榄油）之前（空腹）以及之后7、11（非空腹）、24、48、72、168和336 h（空腹）采集。在3名受试者中，还采集了呼气样本，并在最初12 h内每小时测量二氧化碳生成量。受试者保持其习惯饮食。通过气相色谱-燃烧-同位素比值质谱法（GC-C-IRMS）测量血浆(13)C富集度，通过气相色谱/火焰离子化检测法（GC/FID）测量脂肪酸组成。
马斯特里赫特大学人类生物学系。
通过当地广告招募的3名男性和3名女性。
摄入示踪剂后5 h，血浆总脂质中C18:2n-6的示踪剂/被示踪物比值（TTR）就已升高。(13)C18:2n-6的平均峰值量（±标准误）（3.4±0.8 mg；占剂量的7.6%）在约17 h后出现，(13)C18:3n-6（0.018±0.008 mg；占剂量的0.04%）在7 - 48 h后出现，(13)C2（0:3n-6 0.028±0.011 mg；占剂量的0.06%）在48 - 336 h后出现。C20:4n-6达到TTR峰值的时间因受试者而异，平均为0.022±0.006 mg（占剂量的0.05%）。12 h后呼出气体中回收的(13)C18:2n-6比例在16.8%至25.1%之间。
这些发现表明，单次大剂量45 mg U-(13)C18:2n-6可用于研究(13)C18:2n-6的氧化。然而，由于C20:4n-6的TTR较低，建议使用更高剂量来研究(13)C18:2n-6向LCPs的转化。此外，由于在血浆总脂质和呼出气体中的(13)CO2中仅发现约35%的示踪剂，可能有必要研究其他可获取的脂质组分，以研究亚油酸的整体转化。
