Jenssen T, Nurjhan N, Consoli A, Gerich J E
Department of Medicine, University Hospital of Tromso, Norway.
Eur J Clin Invest. 1993 Aug;23(8):448-54. doi: 10.1111/j.1365-2362.1993.tb00789.x.
Lactate is the predominant gluconeogenic precursor in man. To determine the dose-response relationships between plasma lactate concentration and rates of lactate incorporation in plasma glucose (lactate gluconeogenesis, LGN), we infused 17 normal volunteers with sodium lactate for 180 min at rates ranging from 6 to 40 mumol kg-1 min-1 and measured [U-14C]lactate incorporation into plasma glucose, as well as rates of lactate and glucose appearance in plasma. With the highest lactate infusions, plasma lactate increased up to 7 mM (compared to 1.1 +/- 0.13 mM during control sodium bicarbonate infusions, n = 10) and LGN averaged 4.73 +/- 0.23 mumol kg-1 min-1 (compared to 1.57 +/- 0.26 mumol kg-1 min-1 in bicarbonate control experiments, P < 0.001). The data relating plasma lactate concentration to LGN best fit a sigmoidal curve which plateaued at plasma lactate concentrations of approximately 6 mM and yielded an ED50 of 2.04 +/- 0.20 (SD) mM and a Vmax (6.25 +/- 1.2) (SD) (mumol kg-1 min-1). The sum of the basal rate of lactate appearance and the rate of lactate infusion was not significantly different from the overall rates of lactate appearance during the lactate infusions (35.8 +/- 2.2 vs. 34.8 +/- 2.9 mumol kg-1 min-1, P = 0.23). Thus, our results support the view that infusion of exogenous lactate does not suppress endogenous lactate appearance in plasma.
乳酸是人体中主要的糖异生前体。为了确定血浆乳酸浓度与血浆葡萄糖中乳酸掺入率（乳酸糖异生，LGN）之间的剂量反应关系，我们以6至40μmol·kg⁻¹·min⁻¹的速率给17名正常志愿者输注乳酸钠180分钟，并测量[U-¹⁴C]乳酸掺入血浆葡萄糖的情况以及血浆中乳酸和葡萄糖的生成速率。在最高乳酸输注量时，血浆乳酸浓度升高至7 mM（相比之下，在输注碳酸氢钠对照期间为1.1±0.13 mM，n = 10），LGN平均为4.73±0.23μmol·kg⁻¹·min⁻¹（相比之下，碳酸氢钠对照实验中为1.57±0.26μmol·kg⁻¹·min⁻¹，P < 0.001）。将血浆乳酸浓度与LGN相关的数据最符合一条S形曲线，该曲线在血浆乳酸浓度约为6 mM时达到平稳，ED50为2.04±0.20（标准差）mM，Vmax为(6.25±1.2)（标准差）（μmol·kg⁻¹·min⁻¹）。乳酸生成的基础速率与乳酸输注速率之和与乳酸输注期间乳酸生成的总体速率无显著差异（35.8±2.2对34.8±2.9μmol·kg⁻¹·min⁻¹，P = 0.23）。因此，我们的结果支持这样一种观点，即输注外源性乳酸不会抑制血浆中内源性乳酸的生成。
