Ionic relations and electrical properties of isolated oocytes of Bufo bufo with special reference to removal of extracellular chloride.

1. The efflux rate coefficients of sodium, potassium and chloride from immature oocytes of the toad Bufo bufo have been measured and found to be respectively, 0.0069, 0.0023 and 0.0034 min(-1).2. Replacement of external chloride by sulphate resulted in a fall in chloride efflux of about 50%. This has been interpreted in terms of exchange diffusion.3. The membrane conductance has been measured and found to be 0.14 x 10(-3) mhos cm(-2) in good agreement with the value calculated from the flux data, 0.12 x 10(-3) mhos cm(-2), after taking account of the chloride exchange diffusion fraction.