Figure 2.

The effect of large pulses of InsP₃ on PLCζ or Sr²⁺ triggered Ca²⁺ oscillations. (A) shows an example of the way eggs responded a large uncaging pulse of InsP₃ (3 s UV light at the arrow) by an increase in the frequency of Sr²⁺ triggered Ca²⁺ oscillations (n = 20 eggs). There was a significant increase in frequency of Ca²⁺ spikes from 3.45 (±0.27 sem) in 20 min to 5.05 (±0.35 sem) in 20 min (p < 0.001). In (B) a similar experiment is shown but with PLCζ induced Ca²⁺ oscillations. The sample trace in (B) shows that a 3 s uncaging pulse of InsP₃ (at the arrow) caused an immediate Ca²⁺ increase but no increase in frequency (n = 23 eggs). We analyzed the ability of such pulses to reset the phase of oscillations by measuring then phase shift (PS) and comparing it to time delay (dt) at which the InsP₃ pulse was applied. (C) Illustrates how these values were measured on an actual sample trace. Each value was divided by the time-period (T) for the oscillations in order to normalize the values between different eggs. (D) Shows a plot of these values for all 23 eggs tested.