MEMBRANE POTENTIAL CHANGE AND MEMBRANE CURRENT IN SUPRAMEDULLARY NERVE CELL OF PUFFER

Publisher Website
Google Scholar
Abstract
A spike potential with a peak voltage of 80-100 mv followed by a positive afterpotential appeared in the nerve cell (100-300 [mu] in diameter) when the resting membrane potential (60-70 mv) was decreased by 18-25 mv. The membrane current of the nerve cell associated with a rectangular depolarization obtained by the voltage-clamp technique was characterized by a rapid initial inward surge followed by a gradual increase of the outward current to a final steady value. The initial surge associated with a conductance increase of the membrane to an equivalent membrane e.m.f. which corresponded to the potential level at the peak of the spike, the maximum conductance being 20-30 times the resting conductance of 0.4-1 k [OMEGA] cm2. The outward current associated with a conductance increase to another equivalent e.m.f. which corresponded to a potential level at the peak of the afterpotential. The former conductance change correlated to the spike height and was labile for the change of the experimental condition while the latter change was stable.