Figure 2.

Sustained Ca²⁺_i increases after ZP3 treatment require Ca²⁺_o. Sperm were loaded with fura 2 and incubated in a 1.7 mM Ca²⁺ medium. BAPTA and Ca²⁺ (5 mM) additions served to alternate Ca²⁺_o between >30 nM and 1.7 mM, respectively. ZP3 (10 μg/ml) was added as indicated. Traces are representative of 13–47 cells in these treatment groups. Similar results were obtained with the use of ZP extracts.