| Abstract: | Electrically-operated sodium channels in the somatic membrane of isolated neurons from the rat superior cervical ganglion have been studied by means of intracellular dialysis technique under voltage clamp conditions. It was shown that in this preparation sodium currents can be carried by two independent systems of sodium channels. The mathematical analysis of voltage-dependent TTX-sensitive fast sodium currents was performed by the Hodgkin-Huxley formalism; their kinetic properties were compared with those described in other objects. TTX-sensitive sodium channels in the somatic membrane of sympathetic neurons were found to be highly selective for Na+ ions. Kinetic and voltage-dependent characteristics of slow TTX-resistant sodium current were also described. This component of the sodium current was observed only in a few neurons (not more than 2%). |
