Previously, we reported that glucose-deprived astrocytes were highly vulnerable to peroxynitrite (ONOO-). Here we demonstrate that the increased vulnerability caused by glucose deprivation and ONOO- depends on intracellular pH. The ONOO- releasing reagent 3-morpholinosydnonimine (SIN-1) markedly induced the release of lactate dehydrogenase (LDH, the marker of cytotoxicity) in glucose-deprived astrocytes. Morphological studies and caspase activity assay showed that astrocytes treated together with glucose deprivation and ONOO- died mostly in a necrotic mode. Alkalinization of pH from 7.4 to 7.8 increased LDH release, whereas acidification from pH 7.4 to 7.0 decreased it. However, intracellular pH (pHi), not extracellular pH (pHe), appeared to play a critical role in the synergistic death. Thus, without a change in pHe (7.4) cytosolic acidification by a weak acid salt, sodium acetate, and a Na+/H+ antiporter inhibitor, amiloride, reduced LDH release. In contrast, a weak base, NH4Cl, and a Na+/H + antiporter stimulator, monensin, increased pHi and greatly enhanced LDH release. The augmented death was found to be due, in part, to the preceding decrease in the level of reduced glutathione, the ONOO - scavenger, and collapse of the mitochondrial transmembrane potential at alkaline pH.
|Number of pages||10|
|Journal||Free Radical Biology and Medicine|
|Publication status||Published - 2004 Oct 15|
Bibliographical noteFunding Information:
This study was supported by a grant of the Korea Health 21 R and D Project (02-PJ1-PG6-AG01-0003) from the Ministry of Health and Welfare and a grant from Brain Research Centre of the 21st Century Frontier Research Program (M103KV010005 03K2201 00510) from the Ministry of Science and Technology, Republic of Korea.
All Science Journal Classification (ASJC) codes
- Physiology (medical)