Simulation of action potential damping produced by anticonvulsant drugs

Anticonvulsant drugs reduce the ability of central neurones to sustain high-frequency repetitive firing of action potentials. In recent years, it has been demonstrated that this effect is primarily due to a Na+ conductance reduction. We have simulated the electrical behaviour of a neurone, including Ca2+ and various K+ conductances. Although a reduction of Na+ conductance produces a progressive reduction until a complete suppression of the action potential bust, a smaller reduction of this conductance is necessary to produce the same effect when the delayed-rectifier K+ conductance and the Ca2+ conductance are concomitantly reduced . The results indicate that the drugs action on conductances other than Na+ is important for determining their anticonvulsant effect on neurones at therapeutic concentrations.