Figure 3.

T channel antagonists inhibit the zona pellucida-dependent increase in Ca_i²⁺. [Ca²⁺]_i/K_d values were determined from fluorescent emission of intracellular fura 2. (A) The effects of zona pellucida glycoproteins on [Ca²⁺]_i/K_d in representative sperm that were incubated in control medium (•) or in medium containing 1 μM pimozide (10-min preincubation; ○). Solubilized zona pellucida glycoproteins were added (ZP, ▾; 50 μg/ml) and rates were determined by regression analysis of the linear portions of the response time courses. Slopes of regression lines are indicated. (B) Rates of [Ca²⁺]_i/K_d responses obtained from experiments similar to that shown in A. Capacitated sperm were incubated for 10 min with indicated concentrations of pimozide or amiloride and then treated with solubilized zona pellucida glycoproteins (50 μg/ml). Control populations were treated with culture medium throughout. Data were obtained from four to six separate experiments, with 7–22 sperm observed per experiment. Average response rates were determined for each experiment and used to determine the indicated mean values (±SEM).