Summers L K, Fielding B A, Herd S L, Ilic V, Clark M L, Quinlan P T, Frayn K N
Oxford Lipid Metabolism Group, Nuffield Department of Clinical Medicine, Radcliffe Infirmary, Oxford OX2 6HE, United Kingdom.
J Lipid Res. 1999 Oct;40(10):1890-8.
Early events in the metabolic processing of dietary triacylglycerol may have an important impact on subsequent development of risk factors for coronary heart disease. We have used structured triacylglycerols containing predominantly stearic or oleic acids at the sn -2 position to probe aspects of the processing of dietary fatty acids presented to adipose tissue in chylomicron-triacylglycerol. Studies were conducted on 14 healthy women who were given meals containing 85 g carbohydrate and 60 g of either of the two structured triacylglycerols in random order. Systemic concentrations and arterio-venous differences across adipose tissue for plasma triacylglycerol and non-esterified fatty acids were measured, together with analysis of the fatty acid composition of the relevant fractions. The stereo-specific structure of the ingested triacylglycerol was largely preserved in chylomicron-triacylglycerol. Systemic concentrations of total and individual non-esterified fatty acids were not significantly different after ingestion of the two fats, nor were their rates of release across adipose tissue. The composition of non-esterified fatty acids released from adipose tissue changed after the meal to reflect more closely the composition of the triacylglycerol ingested, but again no significant differences were observed between the two test meals. There was no detectable release of monoacylglycerol from adipose tissue after either test meal. We conclude that the environment for lipoprotein lipase action in adipose tissue in vivo is likely to be highly organized, such that there is no release of monoacylglycerol, nor preferential uptake or release of fatty acids from chylomicron-triacylglycerol according to the nature or the position within triacylglycerol of the fatty acid.
膳食三酰甘油代谢过程中的早期事件可能对冠心病危险因素的后续发展产生重要影响。我们使用了在sn-2位主要含有硬脂酸或油酸的结构化三酰甘油，来探究乳糜微粒三酰甘油中呈现给脂肪组织的膳食脂肪酸的加工方面。对14名健康女性进行了研究，她们被随机给予含有85克碳水化合物和60克两种结构化三酰甘油之一的餐食。测量了血浆三酰甘油和非酯化脂肪酸在全身的浓度以及跨脂肪组织的动静脉差异，并对相关组分的脂肪酸组成进行了分析。摄入的三酰甘油的立体特异性结构在很大程度上保留在了乳糜微粒三酰甘油中。摄入两种脂肪后，全身总非酯化脂肪酸和个体非酯化脂肪酸的浓度没有显著差异，它们跨脂肪组织的释放速率也没有显著差异。餐后从脂肪组织释放的非酯化脂肪酸的组成发生了变化，以更紧密地反映摄入的三酰甘油的组成，但同样，两种测试餐之间没有观察到显著差异。两种测试餐后，脂肪组织均未检测到单酰甘油的释放。我们得出结论，体内脂肪组织中脂蛋白脂肪酶作用的环境可能高度有序，以至于不会释放单酰甘油，也不会根据脂肪酸在三酰甘油中的性质或位置从乳糜微粒三酰甘油中优先摄取或释放脂肪酸。
