[Electrophysiological study of frog eggs at different stages of development. II) Outward rectification in oocytes at the final stage of vitellogenesis].

Voltage-clamp experiments in full-grown frog oocytes, in a range of membrane potentials from 90 mV negative to 30 mV positive, have revealed the presence of voltage-dependent channels selective for K+, blocked by extracellular TEA. The percentage of open K+-channels increases with membrane depolarizations over a range from -40 mV to +10 mV, thus supporting the outward rectification in the I/V relationship. The current transport through the K+-channels open at different potential levels and in various [K+]o takes place in accordance with the constant-field assumptions. The leakage current of the oocyte membrane was found to be considerable large.