Systemic and forearm triglyceride metabolism - Fate of lipoprotein lipase-generated glycerol and free fatty acids
Systemic and forearm triglyceride metabolism - Fate of lipoprotein lipase-generated glycerol and free fatty acids
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DOI：
10.2337/diabetes.53.3.521
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发表时间：
2004-03-01
期刊：
影响因子：
7.7
通讯作者：
Harris, WS
中科院分区：
文献类型：
--
作者：
Miles, JM;Park, YS;Harris, WS
脂蛋白脂酶（LPL）对人体循环中富含磷脂酰肌醇的脂蛋白的作用所产生的脂解产物的命运知之甚少。我们研究了八个瘦的，健康的男性受试者在一夜禁食后。受试者接受含有甘油骨架和分子脂肪酸部分均标记有H-3的三油酸甘油酯的脂肪乳剂输注; C-14甘油和C-14油酸酯共输注，以定量LPL作用引起的H-3甘油和H-3油酸酯的全身和前臂释放。全血浆甘油三酯（推测主要代表VLDL;提取分数2.6 +/-0.6%，P < 0.005 vs 0）和脂肪乳剂中放射性标记的甘油三酯（乳糜微粒的替代物;提取分数31 +/-4%，P < 0.005 vs 0）均存在显著的前臂摄取。甘油的全身清除率和前臂提取率均大于油酸（分别为P < 0.001和P < 0.02）。LPL产生的甘油的全身和前臂分数释放相似，分别为51 +/- 4和59 1%（NS）。相比之下，LPL产生的油酸酯的前臂分数释放小于全身分数释放（14 +/-2 vs. 36 4%，P < 0.0001）。这些结果表明，有逃逸，或溢出，脂肪分解产物的LPL作用于人体富含磷脂酰肌醇的脂蛋白。他们进一步表明，LPL介导的脂肪酸摄取是一个低效的过程，但在肌肉中可能比在脂肪组织中更有效。
Little is known about the fate of the lipolytic products produced by the action of lipoprotein lipase (LPL) on circulating triglyceride-rich lipoproteins in humans. We studied eight lean, healthy male subjects after an overnight fast. Subjects received infusions of lipid emulsions containing triolein labeled with H-3 on both the glycerol backbone and the fatty acid portion of the molecule; C-14 glycerol and C-14 oleate were coinfused to quantify the systemic and forearm release of H-3 glycerol and H-3 oleate resulting from LPL action. There was significant forearm uptake of both whole plasma triglyceride (presumed to represent primarily VLDL; extraction fraction 2.6 +/- 0.6%, P < 0.005 vs. zero) and radiolabeled triglyceride derived from the lipid emulsion (a surrogate for chylomicrons; extraction fraction 31 +/- 4%, P < 0.005 vs zero). Systemic clearance and forearm fractional extraction of glycerol was greater than that of oleate (P < 0.001 and P < 0.02, respectively). The systemic and forearm fractional release of LPL-generated glycerol were similar at 51 +/- 4 and 59 1%, respectively (NS). In contrast, the forearm fractional release of LPL-generated oleate was less than systemic fractional release (14 +/- 2 vs. 36 4%, P < 0.0001). These results indicate that there is escape, or spillover, of the lipolytic products of LPL action on triglyceride-rich lipoproteins in humans. They further suggest that LPL-mediated fatty acid uptake is an inefficient process, but may be more efficient in muscle than in adipose tissue.