| Abstract: | Kinetic and steady-state characteristics of aconitine-modified sodium channels were studied in the Ranvier node membrane. Aconitine-modified sodium channels are shown to be inactivated only partially. The voltage dependence of the fraction of noninactivated channels (h infinity) may be described by a three-state model of the channel with closed, open and inactivated states. A reasonable agreement with the data was obtained when parameters of the inactivated state were supposed to be not changed after aconitine modification of the channels. The membrane repolarization to -70 divided by -110 mV, after long (10 ms) depolarizing shift induces firstly fast current decay ("tail") and then its rather slow increase to a steady-state level. Kinetics of this current requires two or more open states to be postulated. |
