Figure 2.

Exogenous pyruvate enhances ATP production and tyrosine phosphorylation in human spermatozoa. Purified human spermatozoa were incubated under capacitating conditions in the presence of 5 mM glucose and increasing concentrations (28 nM–5 mM) of pyruvate for (A) 30 and (B) 120 min. The data sets are presented as mean ± SEM from four separate experiments (n= 12). (C) Sperm capacitation was confirmed by an increase in total tyrosine phosphorylation compared with spermatozoa incubated under non-capacitating conditions (0 min). The increase in tyrosine phosphorylation levels by 5 mM pyruvate (+) was measured after 30 and 120 min. Total tyrosine phosphorylation levels were detected by immunoblotting with pY antibodies. An antibody against α-tubulin was used as a loading control.