GLUCOSE METABOLITES IN BRAIN AND THE RELATIONSHIP TO 2-DEOXYGLUCOSE METHOD

葡萄糖-6-磷酸脱磷酸化的大小 本报告对活体脑进行了重新检测。从质量上讲， 通过比较~3H-葡萄糖/~(14)C-葡萄糖的比值来考察反应。 注射后1-10分钟脑组织和血液中的葡萄糖 (2-~3H)-和(U-14C)-葡萄糖。目前的研究结果表明，我们的 脑葡萄糖中~3H/~(14)C比值降低35%的先前结果 注射后5分钟未被检测到 在分离过程中，污染物与葡萄糖一起洗脱。 在本研究中，使用改进的分馏程序， 我们发现，脑中~3H/~(14)C比值的下降速度 血糖显著高于血糖中的葡萄糖； 两个时间段的坡度差异为29%。 在定量上，葡萄糖-6-磷酸的去磷酸化是 根据在事件发生后第一分钟内获得的数据进行研究 注射示踪剂。放射性代谢物的形成 来自(2-~3H)-葡萄糖的含量显著大于来自(U-14C)-的。 注射后即刻血糖，S 10点25%，S 21%， S注射后30岁时为14%。下降的趋势是 由血液循环中的氚水流失引起的。这一速度 根据初始形成速率计算的葡萄糖利用率 来自(2-~3H)-葡萄糖的放射性代谢物是1.04 (U-14C)-葡萄糖为0.83umol/min/g。 0.21mol/min/g的差异归因于 大脑中葡萄糖-6-磷酸的去磷酸化。当前 这些发现重申了我们之前的结论，即在大脑中， 葡萄糖-6-磷酸的去磷酸化是活跃的。因为. 脑内葡萄糖快速周转速度与快速平衡 体内标记的葡萄糖在血液循环中的辅助作用，数据 如Nelson等人所报道的，在注射后2分钟获得。 (Nelson，T.，Lucignani，G.，Atlas，S.，Crane，A.M.，Dienel，G.A.， 和Sokoloff，L.：葡萄糖-6-磷酸酶的重新检测 活体中的大脑活动：没有证据表明循环是无效的。科学 229：60-62,1985)不足以得出数量上的结论 葡萄糖-6-磷酸的去磷酸化方面。

The magnitude of the dephosphorylation of glucose-6-phosphate in brain in vivo was reexamined in this report. Qualitatively, the reaction was examined by comparing the ratio of 3H-glucose/14C- glucose in brain and blood from 1 to 10 min after an injection of (2-3H)- and (U-14C)-glucose. Current findings show that our previous result of a 35% decrease in 3H/14C ratio in brain glucose 5 minutes after the injection was caused by undetected contaminants coeluted with glucose in the isolation process. Using an improved fractionation procedure, in the present study, we found that the rate of decrease of the 3H/14C ratio in brain glucose is significantly greater than that in blood glucose; the difference in slopes of the two time-courses was 29%. Quantitatively, the dephosphorylation of glucose-6-phosphate was studied from data obtained within the first minute after the injection of tracers. The formation of radioactive metabolites from (2-3H)-glucose is significantly greater than from (U-14C)- glucose immediately following the injection, 25% at 10 s, 21% s, and 14% at 30 s after the injection. The decreasing trend is caused by loss of tritiated water to blood circulation. The rate of glucose utilization calculated from the initial rates of formation of radioactive metabolites from (2-3H)-glucose was 1.04 umol/min/g; from (U-14C)-glucose was 0.83 umol/min/g. The difference of 0.21 mol/min/g was attributed to the dephosphorylation of glucose-6-phosphate in brain. Current findings reaffirm our previous conclusion that in brain, the dephosphorylation of glucose-6-phosphate is active. Because of rapid rate of glucose turnover in brain and the rapid equilibration of labeled glucose in the body aided by blood circulation, data obtained 2 min after the injection as reported by Nelson et al. (Nelson, T., Lucignani, G., Atlas, S., Crane, A.M., Dienel, G.A., and Sokoloff, L.: Re-examination of glucose-6-phosphatase activity in brain in vivo: No evidence for a futile cycle. Science 229: 60-62, 1985) are not sufficient to conclude the quantitative aspect of the dephosphorylation of glucose-6-phosphate.