Figure 4.

Calcium ionophore can rescue membrane retrieval activity in agatoxin-blocked cells. (A) Sea urchin eggs were incubated in DC-ASW containing 100 μM TMR-Dex, either 9.3 mM CaCl₂ (open bars) or 15 mM CaCl₂ (filled bars) and with or without 50 nM ω-agatoxin TK. Eggs were activated with either sperm, A23187, or ionomycin, and the amount of membrane retrieval was assayed 15 minutes after activation. All points are mean ± SEM, n = 6. (B) Sea urchin eggs were incubated in DC-ASW (ranging from 9.3 mM to 20 mM CaCl₂) containing 100 μM TMR-Dex, and either 0 (filled symbols) or 50 nM (open symbols) ω-agatoxin TK. Eggs were activated with either A23187 (squares) or ionomycin (circles), and the amount of membrane retrieval was assayed 15 minutes after activation. All points are mean ± SEM, n = 6.