In order to manifest the presence of Na-K pump and its property on the unfertilized egg membranes of mouse, membrane potential was recorded under the physiological condition (at 37℃ and 4mM Ca^(2+)). After an induction of superovulation, the fresh eggs with zona pellucida were collected from mouse oviduct. Transient hyperpolarization as pump action was recorded after the switch into the high potassium perfusate (15mM K^+) from K-free perfusate, and the difference between membrane potential observed just before the perfusion of high potassium solution and the maximal membrane potential during the perfusion of high potassium solution was regard as pump activities.
The results observed were as follows,
1. Resting mombrane potential was depolarized under the treatment of 10^(-5)M ouabain.
2. Pump activities of the unfertilized mouse eggs were -3.38±0.61㎷ (Mean±SD, n=6), recorded as transient hyperpolarization due to the electrogenic property.
3. Pump activities were blocked by both treatment of 10^(-5)M ouabain and perfusion of Nafree solution, while increased by high Na^+ (300㎚) perfusion (-7.45±0.75㎷, n=2).
4. Hyperpolarization due to pump activity was nor. altered by Mn^(2+).
5. Above results confirm the presence of ouabain-sensitive Na-K pump, which affected the membrane potential directly, on the unfertilized egg membranes of mouse.
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