The effects of magnesium cation on slow vacuolar (SV) channel currents in radish were studied using the whole-vacuole patch-clamp technique. In the presence of Ca^2＋ buffer EGTA, cytosolic Mg^2＋could not activate SV currents instead of cytosolic Ca^2＋. Mg^2＋added to bath solution caused a decrease of SV currents in a concentration-dependent manner. The concentration response curve could be fitted to a Hill equation with a K_i of (1.94±0.11) mmol/L. Varying the luminal Mg^2＋concentration had no effect on SV currents. These results will provide an important basis at channel level for the further research of the effects of magnesium on physiological activities of plants.

Key words: SV channel, cytosolic Mg^2＋, patch-clamp, vacuole