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Adenosine, Inosine, and Guanosine Protect Glial Cells During Glucose Deprivation and Mitochondrial Inhibition: Correlation Between Protection and ATP Preservation
Author(s) -
Jurkowitz Marianne S.,
Litsky Monica L.,
Browning Megan J.,
Hohl Charlene M.
Publication year - 1998
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1998.71020535.x
Subject(s) - inosine , guanosine , viability assay , purine nucleoside phosphorylase , nucleoside , adenosine , biology , biochemistry , adenosine triphosphate , microbiology and biotechnology , cell , chemistry , purine , enzyme
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 g lucose d eprivation and m itochondrial 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 µ M . 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 µ M 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 µ M 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.