Effects of a pulsing electric signal on the cross membrane potential and the cell division potentiality of a single cell of tobacco

Abstract

A pulsing electric signal (pulse width 10 s) was applied to a single cell of cultured tobacco, line BY-2, by inserting a multifunctional microelectrode (MME) into the cell. The electric voltage (V_ET) was loaded between the electrode terminals of the MME and the reference electrode situated in the extracellular medium. Since the electrical impedance of the MME was as large as that of the cell membrane, the effective potential acting across the cell membrane (V_CMP) should be only some portion of V_ET. The MME enabled simultaneous measurement of V_ET and V_CMP. When V_ET was varied from 0 to −1 V, V_CMP changed linearly in proportion to V_ET. When V_ET variation range was enlarged (from 0 to −2 V), V_CMP changing pattern became a declined curve. When V_ET variation range was further enlarged (from 0 to −5 V), the V_CMP changing pattern showed a saturation curve. Under this condition, the cell division potentiality decreased accordingly. Based on these results, the feasibility of V_CMP as an indicator of the effective intensity of an electric stress signal is discussed. In the present case of a BY-2 cell, a proper intensity of V_CMP that could cause an appreciable stress and not a lethal signal was estimated as −250 mV.