Figure 7. ATP and NDH/NADPH production is dependent on the substrate and the pHi.
A, Sperm prepared as described in the Materials and Methods section were transferred to buffer HS which was supplemented with 1.3 mM 2DG (filled triangles), 10 mM lactate (filled circles), 10 mM lactate +15 mM MA (filled squares), 5 mM glucose (open circles) or 5 mM glucose +15 mM MA (open triangles). The ATP content was determined at t = 0, 5, 10, 20 and 30 min. Each line represents mean values±s.e. of 4 independent experiments. Significant changes were analyzed relating to t = 0 min of the respective plot with **p<0.05 and ***p<0.001. B, At t = 0, sperm were starved out and directly homogenized in HS buffer with pH 6.8 or pH 7.1. After starvation, sperm were further incubated in buffer containing energy substrates as indicated before being homogenized. Absorption at 340 nm was measured over 200 s. Each bar represents mean values±s.e. of 2 independent experiments. *p<0.1 and ***p<0.001.