TABLE 2

Effects of t-boc-Ala on doxorubicin content and H2O2 formation in H9c2 cardiomyocytes: dependence on doxorubicin concentration Subconfluent H9c2 cardiomyocytes (50 × 103) were exposed for 16 h to 0.5 or 5 μM doxorubicin, with or without a prior 2-h loading with 10 mM t-boc-Ala. Cell viability was measured by the antimycin A-inhibitable MTT reduction assay, whereas intracellular doxorubicin and DCF-detectable H2O2 were measured by HPLC, as described under Materials and Methods. Hydrogen peroxide was expressed as the net increase over appropriate controls with or without t-boc-Ala loading. The values are means ± S.E. of three experiments.

Treatment
Viability
Intracellular Doxorubicin
Doxorubicin-Derived H2O2
% nmol/mg protein
0.5 μ M Doxorubicin 105 ± 3 0.02 ± 0.004 0.007 ± 0.002
+ 10 mM t-boc-Ala 44 ± 8* 0.38 ± 0.10* 0.033 ± 0.002*
5 μ M Doxorubicin 51 ± 7* 0.37 ± 0.08* 0.029 ± 0.003*
+ 10 mM t-boc-Ala
33 ± 13*
0.30 ± 0.06*†
0.035 ± 0.005*†

  • ↵* p < 0.01 for (0.5 μM + 10 mM t-boc-Ala) and 5 μM doxorubicin or (5 μM doxorubicin + 10 mM t-boc-Ala) vs. 0.5 μM doxorubicin alone

  • ↵† p > 0.05 for (5 μM + 10 mM t-boc-Ala) vs. 5 μM doxorubicin alone