Spontaneous and induced changes in the membrane potential and resistance ofAcetabularia mediterranea.

The normal resting potential across theAcetabularia mediterranea cell membrane is -170 mV and the resistance is about 0.1 kΩ·cm(2). The time courses of potential and resistance changes have been studied in connection with several slow dynamic properties of the membrane. These effects include spontaneous and stimulated depolarizing spikes, spontaneous repolarization after prolonged maintenance of a quasistable depolarized condition, and a hyperpolarizing response when current is applied to the cell in this depolarized state. These processes show considerable similarities to each other, which suggests that they might all be explained by changes in permeability to Cl(-). In normal conditions, membrane punch-through occurs with a relatively small hyperpolarizing bias.