Jansson S E, Härkönen M H, Helve H
Acta Physiol Scand. 1979 Nov;107(3):205-12. doi: 10.1111/j.1748-1716.1979.tb06464.x.
Energy metabolism was studied in nerve endings isolated from 3-week-old rat brain. Concentrations of glycogen, glucose, ATP, phosphocreatine and lactate were lower in synaptosomes than in the intact brain. The consumption of these endogenous substrates, the ability to generate high-energy phosphate, and the production of ammonia were determined in aerobic and anaerobic conditions. Unlike nerve tissue in general, synaptosomes preferentially utilized endogenous ATP and phosphocreatine stores which, on incubation in the absence of exogenous substrates, were emptied long before glycogen stores were exhausted. The optimal medium for respiratory studies was found to have electrolyte concentrations equal to the extracellular fluid. The synaptosomes had an endogenous respiration rate of 6.3 nmol O2 mg prot. min, measured with an oxygen electrode, and it probably reflects consumption of their glycogen stores. Glucose usually had no effect on the respiration rate of synaptosomes, but sometimes increased it slightly. However, after incubation in the presence of arsenate synaptosomes showed an increase in respiration when glucose was added. ADP, when added with glucose, also stimulated respiration. Pyruvate and succinate always increased respiration, succinate usually having the stronger effect. The present results show that isolated nerve endings are metabolically intact, which justifies their use in research on neurotransmission. In addition, opposite to the present consensus, synaptic transmission does not seem primarily to depend on the availability of glucose but rather on local stores of high-energy phosphate compounds.
对从3周龄大鼠大脑分离出的神经末梢的能量代谢进行了研究。突触体中糖原、葡萄糖、三磷酸腺苷（ATP）、磷酸肌酸和乳酸的浓度低于完整大脑中的浓度。在有氧和无氧条件下测定了这些内源性底物的消耗、产生高能磷酸的能力以及氨的产生。与一般神经组织不同，突触体优先利用内源性ATP和磷酸肌酸储备，在没有外源底物的情况下孵育时，这些储备在糖原储备耗尽之前很久就被耗尽了。发现用于呼吸研究的最佳培养基的电解质浓度与细胞外液相等。用氧电极测量，突触体的内源性呼吸速率为6.3 nmol O2 mg蛋白·分钟，这可能反映了它们糖原储备的消耗。葡萄糖通常对突触体的呼吸速率没有影响，但有时会使其略有增加。然而，在砷酸盐存在下孵育后，添加葡萄糖时突触体的呼吸增加。与葡萄糖一起添加时，二磷酸腺苷（ADP）也刺激呼吸。丙酮酸和琥珀酸总是会增加呼吸，琥珀酸的作用通常更强。目前的结果表明，分离出的神经末梢在代谢上是完整的，这证明了它们在神经传递研究中的应用是合理的。此外，与目前一致的观点相反，突触传递似乎主要不依赖于葡萄糖的可用性，而是依赖于高能磷酸化合物的局部储备。
