Merrill D K, Guynn R W
Brain Res. 1981 Sep 28;221(2):307-18. doi: 10.1016/0006-8993(81)90780-0.
This study has investigated the feasibility of calculating the cytoplasmic free [NADP+]/[NADPH] ratio in rat brain. The time course of the change in the substrate ratios of the malate dehydrogenase (decarboxylating) [E.C. 1.1.1.40], NADP+-isocitrate dehydrogenase (decarboxylating) [E.C. 1.1.1.42] and 6-phosphogluconate dehydrogenase (decarboxylating) [E.C. 1.1.1.44] reactions was followed for up to 10 min after a single, unmodified electroconvulsive seizure. From the results it has been concluded that during periods of low flux, the direction and magnitude of the change in the cytoplasmic free [NADP+]/[NADPH] ratio can, in fact, be reasonably determined even though there is some uncertainty in the absolute value of the ratio itself. It is recommended that reliance not be placed on a single enzyme system but that one or both of the other systems also be observed under a given experimental condition to increase confidence in the determination. The results also demonstrate that seizure and anoxia have a far lesser effect on the cytoplasmic free [NADP+]/[NADPH] ratio than on the free [NAD+]/[NADH] ratio in the same compartment. These results suggest that the pathways using the nicotinamide-adenine dinucleotide phosphate system are relatively protected from the rapid fluctuations that seizure and anoxia can produce.
本研究调查了计算大鼠脑细胞质游离[NADP⁺]/[NADPH]比值的可行性。在单次未改良的电惊厥发作后，追踪苹果酸脱氢酶（脱羧）[E.C. 1.1.1.40]、NADP⁺ -异柠檬酸脱氢酶（脱羧）[E.C. 1.1.1.42]和6 -磷酸葡萄糖酸脱氢酶（脱羧）[E.C. 1.1.1.44]反应底物比值变化的时间进程长达10分钟。从结果得出结论，在低通量时期，尽管细胞质游离[NADP⁺]/[NADPH]比值的绝对值存在一定不确定性，但该比值变化的方向和幅度实际上可以合理确定。建议不要仅依赖单一酶系统，而是在给定实验条件下观察其他一个或两个系统，以增强测定的可信度。结果还表明，与同一区室中游离[NAD⁺]/[NADH]比值相比，癫痫发作和缺氧对细胞质游离[NADP⁺]/[NADPH]比值的影响要小得多。这些结果表明，使用烟酰胺腺嘌呤二核苷酸磷酸系统的途径相对受保护，免受癫痫发作和缺氧可能产生的快速波动影响。
