Kam W, Kumaran K, Landau B R
J Lipid Res. 1978 Jul;19(5):591-600.
Contributions of omega-oxidation to overall fatty acid oxidation in slices from livers of ketotic alloxan diabetic rats and of fasted monkeys are estimated. Estimates are made from a comparison of the distribution of 14C in glucose formed by the slices from omega-14C-labeled compared to 2-14C-labeled fatty acids of even numbers of carbon atoms and from [1-14C]acetate compared to [2-14C]acetate. These estimates are based on the fact that 1) the dicarboxylic acid formed via omega-oxidation of a omega-14C-labeled fatty acid will yield [1-14C]acetate and [1-14C]succinate on subsequent beta-oxidation, if beta-oxidation is assumed to proceed to completion; 2) only [2-14C]acetate will be formed if the fatty acid is metabolized solely via beta-oxidation; and 3) 14C from [1-14C]acetate and [1-14C]succinate is incorporated into carbons 3 and 4 of glucose and 14C from [2-14C]acetate is incorporated into all six carbons of glucose. From the distributions found, the contribution of omega-oxidation to the initial oxidation of palmitate by liver slices is estimated to between 8% and 11%, and the oxidation of laurate between 17% and 21%. Distributions of 14C in glucose formed from 14C-labeled palmitate infused into fasted and diabetic rats do not permit quantitative estimation of the contribution of omega-oxidation to fatty acid oxidation in vivo. However, the distributions found also indicate that, of the fatty acid metabolized by the whole animal in the environment of glucose formation, at most, only a minor portion is initially oxidized via omega-oxidation. As such, omega-oxidation cannot contribute more than a small extent to the formation of glucose.
评估了ω-氧化对酮症性四氧嘧啶糖尿病大鼠和禁食猴子肝脏切片中整体脂肪酸氧化的贡献。通过比较ω-14C标记的偶数碳原子脂肪酸与2-14C标记的脂肪酸以及[1-14C]乙酸盐与[2-14C]乙酸盐在切片中形成的葡萄糖中14C的分布来进行评估。这些评估基于以下事实：1）如果假定β-氧化进行到底，通过ω-14C标记的脂肪酸的ω-氧化形成的二羧酸在随后的β-氧化中将产生[1-14C]乙酸盐和[1-14C]琥珀酸盐；2）如果脂肪酸仅通过β-氧化代谢，则仅会形成[2-14C]乙酸盐；3）[1-14C]乙酸盐和[1-14C]琥珀酸盐中的14C被并入葡萄糖的碳3和碳4中，而[2-14C]乙酸盐中的14C被并入葡萄糖的所有六个碳中。根据发现的分布，估计ω-氧化对肝脏切片中棕榈酸酯初始氧化的贡献在8%至11%之间，对月桂酸酯氧化的贡献在17%至21%之间。从注入禁食和糖尿病大鼠体内的14C标记棕榈酸酯形成的葡萄糖中14C的分布，无法对ω-氧化对体内脂肪酸氧化的贡献进行定量评估。然而，发现的分布也表明，在葡萄糖形成环境中由整个动物代谢的脂肪酸中，至多只有一小部分最初通过ω-氧化被氧化。因此，ω-氧化对葡萄糖形成的贡献至多只能是很小的一部分。
