Vind C, Grunnet N
Biochim Biophys Acta. 1982 Jun 8;720(3):295-302. doi: 10.1016/0167-4889(82)90054-4.
This paper describes the transfer of tritium from [2-(3)H]xylitol or (1R)-[1-(3)H]ethanol into lactate in cells from fed rats either untreated or triiodothyronine-treated. The labelling pattern of lactate during the metabolism of [2-(3)H]xylitol or (1R)-[1-(3)H]ethanol follows the equation L = K(1 - e-t/tau) (mumol tritium/mumol lactate). The yield in lactate together with the minimum value of the total flux of reducing equivalents are used to estimate the specific radioactivity of NADH. We have calculated the lactate dehydrogenase-catalysed oxidation rate of NADH from the experimental values of lactate labelling and the specific radioactivity of NADH. We found the calculated flux of reducing equivalents from NADH to pyruvate to be of the same order of magnitude whether labelled ethanol or labelled xylitol was metabolized. We found the flux to be only a few percent of the maximal activity of lactate dehydrogenase. The results obtained suggest that the cytoplasm can be regarded as one compartment, containing a single pool of NAD(H).
本文描述了氚从[2-(³H)]木糖醇或(1R)-[1-(³H)]乙醇转移至未处理或经三碘甲状腺原氨酸处理的喂食大鼠细胞中的乳酸盐的过程。[2-(³H)]木糖醇或(1R)-[1-(³H)]乙醇代谢过程中乳酸盐的标记模式符合方程L = K(1 - e⁻ᵗ/ᵗₐᵤ)（微摩尔氚/微摩尔乳酸盐）。乳酸盐的产量以及还原当量总通量的最小值用于估算NADH的比放射性。我们根据乳酸盐标记的实验值和NADH的比放射性计算了乳酸脱氢酶催化的NADH氧化速率。我们发现，无论代谢的是标记乙醇还是标记木糖醇，计算得出的从NADH到丙酮酸的还原当量通量在数量级上相同。我们发现该通量仅为乳酸脱氢酶最大活性的百分之几。所得结果表明，细胞质可被视为一个区室，包含单一的NAD(H)池。
