Table 1.

Content of glutathione in cell lysates and cell viability before and after incubation of neurons in the presence of cysteine, CysGly, or γGluCys

Incubation time (hr)	Presence of	GSx content (nmol GSx/mg protein)	GSSG content (nmol GSx/mg protein)	Viability (%)
0		15.9  ± 0.3	0.4  ± 0.3	100.0  ± 8.6
4	Gln	13.6  ± 0.5	0.2  ± 0.1	101.0  ± 1.7
4	Gln + Cys + Gly	38.4  ± 1.0	0.1  ± 0.2	94.4  ± 1.7
4	Gln + CysGly	39.2  ± 0.9	0.1  ± 0.2	96.7  ± 0.5
4	γGluCys + Gly	37.9  ± 0.6	0.4  ± 0.2	94.0  ± 4.0

Neuron-rich primary cultures (5-d-old) were incubated for 4 hr in MM+ containing the amino acids or dipeptides indicated in concentrations of 1 mm. The data presented are triplicates ± SD. The experiment was repeated on an independent culture with comparable results.