Miller A L, Corddry D H
J Neurochem. 1981 Mar;36(3):1202-10. doi: 10.1111/j.1471-4159.1981.tb01719.x.
Brain glucose metabolism was studied in developing rats at ages 10 and 20 days postnatal under normal and hypercapnic conditions. Brains were removed and frozen within 1 s with a freeze-blowing apparatus. Glucose utilization was measured with [2-14C]glucose and [3H]deoxyglucose as tracers. Metabolites were determined by standard enzymatic techniques. Data from [3H]deoxyglucose phosphorylation indicated that normal brain glucose utilization increased almost threefold between the 10th and 20th postnatal days. From the relative rates of utilization of the two isotopes in the 20-day-old control group, it appeared that about 25% of 14C label derived from metabolism of [2-14C]glucose was lost from brain (probably as lactate) rather than entering the Krebs cycle. Under hypercapnic conditions (20% CO2-21% O2-59% N2), rates of glucose utilization by brain were decreased by one-half at both ages and there were progressive decreases in the concentrations of many intermediary metabolites. The bases for concluding that these metabolites were used to supplement glucose as a fuel for respiration, rather than being lost by leakage into blood, are discussed. Despite the differences in brain glucose metabolism between 10-day-old and 20-day-old rats, their responses to hypercapnia are remarkably similar: Rates of glucose utilization are reduced to approximately the same proportion of the original rate by 20% CO2, and endogenous metabolites (particularly glutamate and lactate) appear to be oxidized as replacement fuels.
在出生后10天和20天的发育中大鼠，于正常和高碳酸血症条件下研究脑葡萄糖代谢。取出大脑，并用冷冻吹气装置在1秒内将其冷冻。用[2-¹⁴C]葡萄糖和[³H]脱氧葡萄糖作为示踪剂测量葡萄糖利用情况。代谢物通过标准酶促技术测定。来自[³H]脱氧葡萄糖磷酸化的数据表明，出生后第10天到第20天之间，正常脑葡萄糖利用增加了近三倍。从20日龄对照组中两种同位素的相对利用速率来看，似乎源自[2-¹⁴C]葡萄糖代谢的¹⁴C标记约25%从脑中丢失（可能以乳酸形式），而不是进入三羧酸循环。在高碳酸血症条件下（20% CO₂ - 21% O₂ - 59% N₂），两个年龄段的脑葡萄糖利用速率均降低一半，并且许多中间代谢物的浓度逐渐下降。讨论了得出这些代谢物被用作补充葡萄糖作为呼吸燃料而不是因渗漏到血液中而丢失这一结论的依据。尽管10日龄和20日龄大鼠的脑葡萄糖代谢存在差异，但它们对高碳酸血症的反应非常相似：20% CO₂使葡萄糖利用速率降低到原始速率的大致相同比例，并且内源性代谢物（特别是谷氨酸和乳酸）似乎被氧化作为替代燃料。
