Two modes of activity of nicotinic acetylcholine receptor channels in sympathetic neurons.

Spectral analysis of acetylcholine (ACh) noise was performed in voltage-clamped neurons of the isolated rabbit superior cervical ganglion at 34-37 degrees C and at membrane potential--80 mV. Two modes of activity were found in the ionic channels of nicotinic ACh receptors, with mean channel life-times of for fast-operating channels and for slow-operating channels. Excitatory postsynaptic current (EPSC) decays exponentially with a time constant which is very close to , indicating that the slow-operating channel activity determines the duration of EPSC. The mean value of conductance of single nicotinic ACh-receptor channel is 36 more or less 3 pS.