RESUMO
Using the extracellular recording we studied the effect of 4-aminopyridine (4-AP), a potassium channel blocker on the electrical activity of the myelinated nerve fibres of amphibia Rana ridibunda Pallas. Two main types of the reaction on 4-AP were established: extension of the action potential and multi-spike response. In some cases the nerve fibres with multi-spike response generated spontaneous activity without stimulation in the form of bursts of action potentials. During repetitive stimulation 4-AP decreased after-depolarization (at the beginning of the stimulation), the posttetanic after-depolarization and the development of posttetanic after-hyperpolarization. Using the paired stimulation it was established that the spike and after-depolarization of the second action potential depended on the size of after-depolarization after the first action potential. The effects of 4-AP were strongly time-dependent.
