Single- and multi-channel currents recorded with patch electrodes in mouse eggs.
Zona-free mouse eggs are amenable to patch recording as well as to whole-cell recording (Bland et al., 1984; Peres, 1986a). Although many patches are silent, others show spontaneous channel opening; the single channel current is 1.5 pA and inwardly directed at resting potential (RP). Current amplitudes distribute normally as a single population at RP, however at RP-50 mV the amplitude histogram indicates two channel populations. Open time distribution is exponential with a mean open time between 4 and 7 msec at RP. In three cases out of thirty-eight, in which depolarizations were given from a holding potential of RP-50 mV, microscopic currents very similar in kinetics and voltage-dependence to the whole-cell Ca2+ current were observed. No single-channel currents could be resolved in these traces. The results reported here indicate that the voltage-dependent Ca2+ current of the mouse egg goes through low-conductance channels located in high density spots on the egg surface.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000502:physiology; D004553:Electric Conductivity; D005260:Female; D007473:Ion Channels / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials; D051379:Mice; D010063:Ovum / Q000502:physiology*
D007473:Ion Channels; D002118:Calcium