膜片钳法研究镁离子对萝卜液泡膜SV通道的影响

用膜片钳全液泡记录方式研究了Mg^2＋对萝卜(Raphanus sativus L.)液泡膜上SV通道电流的影响. 结果表明: 用EGTA配位Ca^2＋后, 胞质Mg^2＋不能够代替Ca^2＋来激活SV通道; 外液中不同浓度的Mg^2＋对通道电流有抑制作用, 并且呈一定的浓度依赖性, 用Hill方程拟合浓度依赖性曲线, 得抑制常数K_i＝(1.94±0.11) mmol/L, 而内液中的Mg^2＋不影响通道电流. 这一结果为进一步研究镁对植物生理活动的影响从通道水平提供了重要依据.

Study of Magnesium Effects on Slow Vacuolar Ion Channel in Radish by Patch-Clamp Technique

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.