Jurkowitz M S, Litsky M L, Browning M J, Hohl C M
Department of Medical Biochemistry, Ohio State University, Columbus 43210, USA.
J Neurochem. 1998 Aug;71(2):535-48. doi: 10.1046/j.1471-4159.1998.71020535.x.
The purpose of this study was to determine the mechanism by which adenosine, inosine, and guanosine delay cell death in glial cells (ROC-1) that are subjected to glucose deprivation and mitochondrial respiratory chain inhibition with amobarbital (GDMI). ROC-1 cells are hybrid cells formed by fusion of a rat oligodendrocyte and a rat C6 glioma cell. Under GDMI, ATP was depleted rapidly from ROC-1 cells, followed on a much larger time scale by a loss of cell viability. Restoration of ATP synthesis during this interlude between ATP depletion and cell death prevented further loss of viability. Moreover, the addition of adenosine, inosine, or guanosine immediately before the amobarbital retarded the decline in ATP and preserved cell viability. The protective effects on ATP and viability were dependent on nucleoside concentration between 50 and 1,500 microM. Furthermore, protection required nucleoside transport into the cell and the continued presence of nucleoside during GDMI. A significant positive correlation between ATP content at 16 min and cell viability at 350 min after the onset of GDMI was established (r = 0.98). Modest increases in cellular lactate levels were observed during GDMI (1.2 nmol/mg/min lactate produced); however, incubation with 1,500 microM inosine or guanosine increased lactate accumulation sixfold. The protective effects of inosine and guanosine on cell viability and ATP were >90% blocked after treatment with 50 microM BCX-34, a nucleoside phosphorylase inhibitor. Accordingly, lactate levels also were lower in BCX-34-treated cells incubated with inosine or guanosine. We conclude that under GDMI, the ribose moiety of inosine and guanosine is converted to phosphorylated glycolytic intermediates via the pentose phosphate pathway, and its subsequent catabolism in glycolysis provides the ATP necessary for maintaining plasmalemmal integrity.
本研究的目的是确定腺苷、肌苷和鸟苷延迟神经胶质细胞（ROC-1）细胞死亡的机制，这些细胞在葡萄糖剥夺和用异戊巴比妥抑制线粒体呼吸链（GDMI）的情况下。ROC-1细胞是由大鼠少突胶质细胞和大鼠C6胶质瘤细胞融合形成的杂交细胞。在GDMI条件下，ATP从ROC-1细胞中迅速耗尽，随后在更长的时间尺度上细胞活力丧失。在ATP耗尽和细胞死亡之间的这段间隙期间恢复ATP合成可防止活力进一步丧失。此外，在异戊巴比妥之前立即添加腺苷、肌苷或鸟苷可减缓ATP的下降并维持细胞活力。对ATP和活力的保护作用取决于核苷浓度在50至1500微摩尔之间。此外，保护需要核苷转运进入细胞以及在GDMI期间持续存在核苷。在GDMI开始后16分钟时的ATP含量与350分钟时的细胞活力之间建立了显著的正相关（r = 0.98）。在GDMI期间观察到细胞乳酸水平适度增加（每分钟产生1.2纳摩尔/毫克乳酸）；然而，用1500微摩尔肌苷或鸟苷孵育会使乳酸积累增加六倍。在用核苷磷酸化酶抑制剂50微摩尔BCX-34处理后，肌苷和鸟苷对细胞活力和ATP的保护作用被阻断>90%。因此，在用肌苷或鸟苷孵育的BCX-34处理的细胞中乳酸水平也较低。我们得出结论，在GDMI条件下，肌苷和鸟苷的核糖部分通过磷酸戊糖途径转化为磷酸化的糖酵解中间产物，其随后在糖酵解中的分解代谢提供维持质膜完整性所需的ATP。
