Table 1.

ATP and [ATP]/[ADP] ratio in the presence of H2O2 and veratridine

ATP nmol/mg[ATP]/[ADP]
Control3.76  ± 0.0037.3  ± 0.23
Veratridine2.95  ± 0.13*6.7  ± 0.26
H2O22.4  ± 0.09*3.77  ± 0.09*
Veratridine + H2O20.52  ± 0.03*1-a0.87  ± 0.06*1-a
Veratridine + H2O2 (no Ca2+)0.48  ± 0.04*0.86  ± 0.04*
Ouabain3.70  ± 0.057.24  ± 0.17
Ouabain + H2O21.77  ± 0.09*1-a3.09  ± 0.20*1-a
Veratridine + ouabain3.7  ± 0.038.19  ± 0.15*
Veratridine + H2O2 + ouabain1.24  ± 0.04*1-b2.72  ± 0.18*1-b

  • Synaptosomes were incubated for 12 min in standard medium, and ATP level and [ATP]/[ADP] ratio were determined at the end of the incubation. Additions were as described for Figure 1. H2O2 (0.5 mm) was applied at 300 sec after addition of veratridine (40 μm) at 100 sec, where indicated. Ouabain (500 μm) was given at 50 sec. “No Ca2+” indicates that the experiment was performed in a medium containing no added Ca2+ and 100 μm EGTA. The control ATP level (without any addition) measured in a Ca2+-free medium was not significantly different (3.85 ± 0.04 nmol/mg; n = 4) from the control shown in the Table. Data are the average of four experiments ± SE (n = 4).

  • *Significantly different compared with the respective control values.

  • ↵F1-a Significantly different compared with values obtained with veratridine or H2O2 alone.

  • ↵F1-b Significantly different compared with the value obtained with veratridine + H2O2(p < 0.001).