Ca2+ regulation of outward rectifying K+ channel in the plasma membrane of tobacco cultured cells in suspension:: a role of the K+ channel in mitigation of salt-stress effects by external Ca2+

The patch-clamp technique was used to study effect of the Ca2+ on K+ channels in the plasma membrane of protoplasts isolated from tobacco (Nicotiana tabacum L., cv. Bright Yellow) cultured cells in suspension. The outward rectifying whole-cell K+ currents were not affected by intracellular Ca2+, but they were reduced with increasing extracellular Ca2+. Neither extracellular nor intracellular Ca2+ affected the permeability ratios (PK+/PNa+) of the plasma membrane, These results suggest that the inhibition of outward-reflecting K+ channels by extracellular Ca2+ may partially contribute towards the mitigation of detrimental effects of salinity on growth by extracellular Ca2+.