Na and Ca spikes produced by ions passing through Ca channels in mouse ovarian oocytes.
Ovarian oocyte membrane of the mouse was found to be excitable. Ca-dependent action potentials, which were blocked by Co2+, indicated the existence of Ca channels. In addition, Na-dependent action potentials were detected in Ca2+-free solution. These Na spikes were insensitive to tetrodotoxin (TTX) and were blocked by Co2+, Cd2+, or La3+, suggesting that the Na+ goes through the Ca channel instead of the Na channel. Such a Na current has not been reported in other eggs. It is concluded that both Na+ and Ca2+ pass through the Ca channels during excitation in mouse ovarian oocytes.
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000502:physiology*; D005260:Female; D007473:Ion Channels / Q000502:physiology*; D051379:Mice; D008813:Mice, Inbred ICR; D009865:Oocytes / Q000378:metabolism*; D010053:Ovary / Q000166:cytology*; D010063:Ovum / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism / Q000502:physiology*
D007473:Ion Channels; D012964:Sodium; D002118:Calcium