Bhuiyan A K, Seccombe D, Bartlett K
Department of Child Health, Medical School, University of Newcastle Upon Tyne, U.K.
Clin Invest Med. 1995 Apr;18(2):144-51.
A sensitive method of continuous on-line radio-high performance liquid chromatography (HPLC) was used to detect the specific radio-labelled acyl-carnitine esters derived from the oxidation of [U-14C]3-methyl-2-oxopentanoate by rat liver and muscle mitochondrial fractions. The recoveries of carnitine, acetyl-carnitine, propionyl-carnitine, 2-methylbutyryl-carnitine, and hexanoyl-carnitine were 98.7% (+/- 5.4; SEM, n = 3), 91.4% (+/- 7.6), 89.4% (+/- 5.2), 84.6% (+/- 6.8), and 87.9% (+/- 7.8), respectively, from quenched mitochondrial incubations. This method demonstrated that rat liver and muscle mitochondria generate acetyl-carnitine, propionyl-carnitine and 2-methylbutyryl-carnitine when incubated with [U-14C]3-methyl-2-oxopentanoate in the presence of carnitine. The production of acetyl-carnitine was almost similar in the 2 tissues. Muscle mitochondria produced higher amounts of propionyl-carnitine and 2-methylbutyryl-carnitine than liver mitochondria. These observations suggest a limited utilization of propionyl-CoA by muscle mitochondria which, through a mechanism of feed-back inhibition, may have contributed to the accumulation of 2-methylbutyryl-CoA. This study provides further evidence for the importance of carnitine in the modulation of the mitochondrial [acyl-CoA/[CoA] pool.
采用一种灵敏的连续在线放射性高效液相色谱法（HPLC），检测大鼠肝脏和肌肉线粒体组分氧化[U-14C]3-甲基-2-氧代戊酸酯所衍生的特定放射性标记的酰基肉碱酯。从淬灭的线粒体孵育物中回收肉碱、乙酰肉碱、丙酰肉碱、2-甲基丁酰肉碱和己酰肉碱的回收率分别为98.7%（±5.4；SEM，n = 3）、91.4%（±7.6）、89.4%（±5.2）、84.6%（±6.8）和87.9%（±7.8）。该方法表明，在肉碱存在的情况下，大鼠肝脏和肌肉线粒体与[U-14C]3-甲基-2-氧代戊酸酯一起孵育时会生成乙酰肉碱、丙酰肉碱和2-甲基丁酰肉碱。乙酰肉碱在这两种组织中的生成量几乎相似。肌肉线粒体生成的丙酰肉碱和2-甲基丁酰肉碱比肝脏线粒体多。这些观察结果表明，肌肉线粒体对丙酰辅酶A的利用有限，通过反馈抑制机制，这可能导致了2-甲基丁酰辅酶A的积累。本研究为肉碱在调节线粒体[酰基辅酶A/辅酶A]池中的重要性提供了进一步的证据。
