Resting membrane potential and action potential of Nitella expansa protoplasts

Inside negative membrane potentials were observed for protoplasts obtained from Nitella expansa leaf internodal cells in media containing 1 to 100 mM CaCl2 using the microelectrode technique. The potential values were less negative than the membrane potential of intact N. expansa leaf internodal cells. In addition, an action potential consisting of two components—a fast component and a slow component—was induced by electrical stimulation for the protoplasts as well as the intact cells.