[The problem of excitability in the works of L. L. Vasil'ev and its further development]

Using microelectrode recording of the mollusks Planorbis corneus and Lymnaea stagnalis neurones, protracted depolarisation current was shown to induce first increased and then decreased excitability. Protracted hyperpolarization current entails a transmembrane potential difference and eliminates the inactivation of ion channels. Rhythmic depolarisation stimulation causes inactivation of inward ion current.