Figure 7

Effect of SNP and PTIO on nitrite levels and doxorubicin toxicity in HT29 iNOS^- cells. HT29 iNOS^- cells and HT29-dx cells were incubated for 3 h in the absence (CTRL) or presence of PTIO (100 μmol/L), SNP (100 μmol/L) or both (PTIO+SNP), then subjected to the following investigations. (A) Nitrite levels in extracellular medium were measured by Griess method as reported in the Methods section. Measurements were done in triplicate and data are represented as mean ± SE (n = 3). Versus CTRL: * p < 0.05; versus SNP: ° p < 0.05. (B). Intracellular accumulation of doxorubicin was measured fluorimetrically in cells incubated in the absence (CTRL) or in the presence of PTIO, SNP and PTIO+SNP, together with 5 μmol/L doxorubicin (see Methods section). The experiments were performed in triplicate and data are represented as mean ± SE (n = 3). Versus CTRL: * p < 0.002; versus SNP: ° p < 0.01. (C) The release of LDH in the cell culture medium was measured in triplicate under the same experimental conditions of point B. In the absence of doxorubicin, neither PTIO nor SNP significantly changed the extracellular activity of LDH towards control cells (data not shown). Data are represented as mean ± SE (n = 4). Versus CTRL: * p < 0.02; versus SNP: ° p < 0.01.