Resting membrane potential and action potential of Nitella expansa protoplasts

Inside negative membrane potentials were observed for protoplastsobtained from Nitella expansa leaf internodal cells in mediacontaining 1 to 100 mM CaCl₂ using the microelectrode technique.The potential values were less negative than the membrane potentialof intact N. expansa leaf internodal cells. In addition, anaction potential consisting of two components—a fast componentand a slow component—was induced by electrical stimulationfor the protoplasts as well as the intact cells. (Received December 18, 1979; )