Figure 7.

Effect of cysteamine (Cya) on cell survival (A) and ³⁵S-cystine uptake and cell survival in glutamate-treated HT22 cells (B). For the measurement of cell survival, cells were treated with 5 mM glutamate alone or in the presence of increasing doses of (A) Cya or (B) 10 μM Cya alone or along with 5 mM BCH, 5 mM d-serine, 5 mM arginine, 5 mM serine, 100 μM TBOA or 5 mM MAIBA. Cell survival was measured after 24 hr by the MTT assay. For the measurement of ³⁵S-cystine uptake, cells were treated with 25 μM ³⁵S-cystine in the presence of 10 μM Cya alone or along with 5 mM BCH, 5 mM d-serine, 5 mM arginine, 5 mM serine, 100 μM TBOA or 5 mM MAIBA which were added to the labeling mixture just before addition to the cells for 10 min. After solubilization of the cells in 0.2 M NaOH, aliquots were taken for scintillation counting and protein determination. Results are the average ± SEM of three independent experiments. * indicates significantly different from Cya alone.