Simulation of the ionic mechanisms of molluscan neurons under pentylenetetrazol-induced effects.

Some effects of the convulsant drug pentylenetetrazol (PTZ) on molluscan neurons were simulated. The calculations were based on the voltage clamp results of Connor and Stevens as well as Williamson and Crill. The normal repetitive state and the PTZ-controlled state were compared and threshold phenomena shown by prolonged depolarizations were studied by injection of hyperpolarizing currents into the first segment of the cable model, which is a widely used description of electrical spread in neuronal membranes. The potassium leakage (concentration per unit area) occurring simultaneously with the fluctuations of the ionic components was also evaluated. It is concluded that the PTZ-controlled state may alter the profile of the potassium leakage both quantitatively and dynamically. The hyperpolarizing and depolarizing current sequences may be functionally related to the intracellular epileptiform discharges.