Figure 10.

Growth restriction by H₂S is due to electron acceptor insufficiency. a, a change in the NAD⁺:NADH ratio was observed in the presence of 0.1 mm Na₂S (gray) compared with its absence (white). The NAD⁺:NADH ratios for untreated HCECs and HT29 cells were set at 1. The data are representative of five independent experiments, each performed in triplicate (*, p < 0.001). b, a difference in the NAD⁺:NADH ratio was observed in HT29^SQRscr (Ctrl) and HT29^SQRkd1 (KD) cells in the absence (white) and presence of 0.1 mm Na₂S (gray). The NAD⁺:NADH ratio for untreated HT29^SQRscr cells was set at 1. The data are representative of mean ± S.D. (error bars) of three independent experiments, each performed in triplicate. The p values are shown for the difference between HT29^SQRscr cells with and without H₂S and between Na₂S-treated HT29^SQRscr and HT29^SQRkd1 cells. The difference between untreated HT29^SQRscr and HT29^SQRkd1 cells was not significant (p > 0.3). c, proliferation of HCECs (white) and HT29 cells (gray) at 48 h following culture in the absence or presence of 0.3 mm Na₂S, uridine (U), pyruvate (Pyr), and aspartate (Asp) added at concentrations specified under “Experimental procedures.” The data are representative of four independent experiments, each performed in triplicate, and represent the mean ± S.D. (*, p < 0.001; **, p < 0.01).