Figure 6.

Ca²⁺ oscillations blocked by propranolol. In (A) an example is shown of a mouse egg undergoing Ca²⁺ oscillations at fertilization where the addition of 300 μM propranolol inhibited subsequent oscillations (n = 13 eggs). Before addition of propranolol the mean frequency was 12.2 ± 1.14 spikes/h with all eggs oscillating. After adding propranolol there were 0.8 ± 0.23 spikes /h (a significant difference from before propranolol, p = < 0.0001). 6/13 eggs stopped oscillating immediately, 4/13 eggs had one Ca²⁺ spike, and 3/13 has 2 spikes in an hour. (B) shows PLCζ cRNA (pipette concentration = 0.02 μg/μl) induced Ca²⁺ oscillations inhibited by propranolol (n = 21 eggs). Before propranolol all eggs oscillated with 4.3 ± 0.46 spikes/h. After addition of propranolol there were 0.95 ± 0.25 spikes/h (a significant difference p < 0.0001). With propranolol, 10/21 eggs stopped Ca²⁺ oscillations, 6/21 showed a single spike, and 5/21 had >1 Ca²⁺ spike. In (C) an example is shown of an egg where PLCζ induced Ca²⁺ oscillations were blocked by the addition of propranolol but then oscillations were restored when propranolol was washed out (typical of n = 8 eggs). Before propranolol, all eggs oscillated with 6.7 ± 1.3 spikes/h. After propranolol this decreased to 1.33 ± 0.29 spikes/h, with all oscillations stopping after 2 spikes. When propranolol was removed there were 10 ± 0.55 spikes in 30 min. Adding propranol and then removing it both caused significant changes in the number of Ca²⁺ spikes (p < 0.001). (D) shows an example of an egg undergoing Ca²⁺ oscillations in response to Sr²⁺ media where propranolol was subsequently added (n = 10 eggs). Before propranolol all eggs oscillated with 4.1 ± 0.29 spikes/h. After adding propranolol all eggs continues to oscillate with 3.9 ± 0.66 Ca²⁺ spikes/h (not significantly different). In (E) an example is shown of an egg undergoing Ca²⁺ oscillations in response to microinjection of 5 μM adenophostin in media that contained 300 μM propranolol form the start of the experiment (n = 8 eggs). In propranolol there were 5.5 ± 0.51 Ca²⁺ spikes 30 min, compared with 10.4 ± 0.71 spikes/30 min (n = 11) for eggs in media with HKSOM. This is significantly different (unpaired t-test, p = < 0.0001).