Change in intracellular -concentration () is an essential event for egg activation and further development. ion is originated from intracellular -store via inositol 1,4,5-triphosphate receptor and/or influx via channel. This study was performed to investigate whether changes in /calmodulin dependent protein kinase II (CaM KII) activity affect influx during artificial egg activation with ethanol using monitoring system and whole-cell patch clamp technique. Under ion-omitted condition, -oscillation was stopped within 30 min post microinjection of porcine sperm factor, and ethanol-induced increase was reduced. To investigate the role of CaM KII known as an integrator of - oscillation during mammalian egg fertilization, CaM KII activity was tested with a specific inhibitor KN-93. In the eggs treated with KN-93, ethanol failed to induce egg activation. In addition, KN-93 inhibited inward current () in a time-dependent manner in whole-cell configuration. Immunostaining data showed that the voltage-dependent channels were distributed along the plasma membrane of mouse egg and 2-cell embryo. From these results, we suggest that influx during fertilization might be controlled by CaM KII activity.