Figure 4. Changes of extra-lenticular level of glutathione under different lens culture conditions. Changes of extra-lenticular level of total glutathione are expressed as Δµmol glutathione, which refers to the difference between the value of extra-lenticular total glutathione (GSH plus GSSG expressed as GSH equivalents) measured at 24 h of incubation and that measured at zero time. Lens incubations were performed in a final volume of 40 ml in the following conditions: A: GSH/Gly-Gly medium; B: GSH/Gly-Gly/SB medium; C: GSH/Gly-Gly/SB medium supplemented with 0.5 mM Cys-Gly; D: GSH/Gly-Gly/SB medium supplemented with 0.5 mM cysteine; E: GSH/Gly-Gly/SB medium supplemented with 0.5 mM γ-Glu-Cys; F: GSH/Gly-Gly medium supplemented with 0.1 mM propargylglycine; G: GSH/Gly-Gly medium supplemented with 2 mM buthionine sulfoximine. See text for details. Values are reported as the mean of at least three different experiments; the error bars represent the standard error of the mean. Statistical analysis was performed by comparing Δµmol glutathione with respect to A (*) or B (#) conditions. (*, #): p<0.05; (**, ##): p<0.01; (***, ###): p<0.001.