Hetenyi G, Ferrarotto C
Biochem J. 1985 Oct 1;231(1):151-5. doi: 10.1042/bj2310151.
To non-anaesthetized rats starved for 3 days, [U-14C]acetone, NaH14CO3, L-[U-14C]lactate, [2-14C]acetate or D-[U-14C]- plus D-[3-3H]-glucose was injected intravenously. From the change in the plasma concentration of labelled acetone versus time after the injection, the metabolic clearance rate of acetone was calculated as 2.25 ml/min per kg body wt., and its rate of turnover as 0.74 mumol/min per kg. The extent and time course of the labelling of plasma glucose, lactate, urea and acetoacetate were followed and compared with those observed after the injection of labelled lactate, acetate and NaHCO3. The labelling of plasma lactate was rapid and extensive. Some 1.37% of the 14C atoms of circulating glucose originated from plasma acetone, compared with 44% originating from lactate. By deconvolution of the Unit Impulse Response Function of glucose, it was shown that the flux of C atoms from acetone to glucose reached a peak at about 100 min after injection of labelled acetone. In comparable experiments the transfer from lactate reached a peak at 14 min after the injection of labelled lactate. It was concluded that acetone is converted into lactate to a degree sufficient to account for the labelling of plasma glucose and is thus a true, albeit minor, substrate of glucose synthesis in starved rats.
给饥饿3天的未麻醉大鼠静脉注射[U-14C]丙酮、NaH14CO3、L-[U-14C]乳酸、[2-14C]乙酸盐或D-[U-14C]-加D-[3-3H]-葡萄糖。根据注射后标记丙酮的血浆浓度随时间的变化，计算出丙酮的代谢清除率为每千克体重2.25毫升/分钟，其周转速率为每千克0.74微摩尔/分钟。追踪血浆葡萄糖、乳酸、尿素和乙酰乙酸的标记程度和时间进程，并与注射标记乳酸、乙酸盐和NaHCO3后观察到的情况进行比较。血浆乳酸的标记迅速且广泛。循环葡萄糖中约1.37%的14C原子来自血浆丙酮，而来自乳酸的为44%。通过对葡萄糖的单位脉冲响应函数进行反卷积分析，结果表明，注射标记丙酮后约100分钟，丙酮到葡萄糖的C原子通量达到峰值。在类似实验中，注射标记乳酸后14分钟，乳酸到葡萄糖的转移达到峰值。得出的结论是，丙酮转化为乳酸的程度足以解释血浆葡萄糖的标记，因此在饥饿大鼠中，丙酮是葡萄糖合成的一种真正（尽管是次要的）底物。
