FIGURE 1.

AR relies on cAMP synthesized by sAC. A, intact (nonpermeabilized) sperm were exposed to the indicated concentrations of KH7 for 15 min at 37 °C. Acrosomal exocytosis was initiated by adding 10 μm A23187 (left), 15 μm progesterone (Pg, right), or 50 μm 8pCPT-2′-O-Me-cAMP (8pCPT, right) and incubating at 37 °C for a further 15 min. Cells were fixed; acrosomal exocytosis was evaluated by FITC-PSA binding, and data were plotted without normalization (mean ± S.E. of at least three independent experiments); **, p < 0.01 compared with A23187 (left) or progesterone (right). B, SLO-permeabilized human sperm were treated for 15 min at 37 °C with increasing concentrations of KH7. AR was subsequently initiated by adding 0.5 mm CaCl₂ and incubating for 15 min at 37 °C. Exocytosis was evaluated by FITC-PSA binding, and data were normalized as described under “Experimental Procedures.” Plotted results represent the mean ± S.E. of at least three independent experiments.