Transient outward K+ currents across the plasma membrane of laticifer fromHevea brasiliensis

Non-inactivating outward rectifying K+ channel currents have been identifie d in a variety of plant cell types and species. The present study of latici fer protoplasts from Hevea brasiliensis, cells which are specialized for st ress response, has revealed, through a switch-clamp method, an outward rect ifying current displaying rapid inactivation. The inactivation depended on the external K+ concentration and on the voltage. This current inactivation appeared clearly different from all those previously described in plant ce lls and it shared homology with current kinetics of animal Shaker family ch annels. These results, given the recent cloning of plant K+ channel beta-su bunits, shed new light on possible plant K+ channel regulation, (C) 1999 Fe deration of European Biochemical Societies.