Fig. 5. Effect of energetic substrates starvation on sperm-triggered [Ca²⁺] oscillations and cellular [ATP]. (A,B) Mature eggs are incubated in M2 medium without lactate, pyruvate, glucose and amino acids for 2 hours and then fertilised. Where indicated, 2 mM pyruvate is added to the dish. The lack of energetic substrates disrupts the sperm-triggered [Ca²⁺] oscillations with either [Ca²⁺]_i remaining high after a Ca²⁺ transient (A, n=12) or with [Ca²⁺]_i remaining low (B, n=11). (C) Changes in [ATP]_i upon withdrawal of energetic substrates (n=7). An egg was placed in M2 medium without energetic substrates for 30 minutes before the start of the recording, then, where indicated, 2 mM pyruvate or 1 µM FCCP was added.