Subcellular localization of glutathione and thermal sensitivity.
Chinese hamster ovary (CHO) cells were exposed to various concentrations of diethylmaleate (DEM) during a 42 degrees C incubation to determine if glutathione (GSH) compartmentalization was a factor in modification of thermal sensitivity. Cytoplasmic and mitochondrial GSH were isolated from CHO cells immediately after a hyperthermic treatment consisting of 2 h at 42 degrees C. Under these experimental conditions differential GSH depletion between the cytosol and mitochondrial compartments were observed. For example, 12 microM DEM was needed to deplete cytoplasmic GSH by 50% compared to 24 microM DEM needed to deplete mitochondrial GSH to the same level. Further, an ln-ln plot of the relative cytosolic GSH concentration vs the DEM concentration indicated a linear relationship (slope = -1.0). In contrast, the mitochondrial GSH plot exhibited a shoulder followed by a linear removal (slope = -0.90). Essentially the two linear curves were parallel. Analysis of thermal dose-response curves for cells exposed to between 10 and 100 microM DEM indicated that cell survival was unaffected by the addition of DEM until a critical concentration was surpassed. This threshold response was interpreted to mean that mitochondrial GSH depletion was the limiting factor.
Freeman
M L
ML
Vanderbilt Center for Radiation Oncology, Nashville, Tennessee.
Meredith
M J
MJ
D000818:Animals; D002460:Cell Line; D002950:Citrate (si)-Synthase / Q000378:metabolism; D006224:Cricetinae; D003593:Cytoplasm / Q000378:metabolism*; D004072:Digitonin / Q000494:pharmacology; D005260:Female; D005978:Glutathione / Q000378:metabolism*; D006358:Hot Temperature; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008298:Maleates / Q000494:pharmacology; D008928:Mitochondria / Q000378:metabolism*; D010053:Ovary
D008298:Maleates; D007770:L-Lactate Dehydrogenase; D002950:Citrate (si)-Synthase; C014476:diethyl maleate; D005978:Glutathione; D004072:Digitonin