Journal of Neuroscience, Vol 6, 590-593, Copyright © 1986 by Society for Neuroscience
Different synaptic channel kinetics in sympathetic B and C neurons of the bullfrog
LM Marshall
Sympathetic ganglia of the frog contain two types of principal neurons, B
and C cells, which are innervated by two distinct classes of cholinergic
preganglionic axons, B and C fibers. This study examined and compared the
kinetics of nicotinic ACh-gated channels that produce the fast excitatory
postsynaptic currents (EPSCs) in B and C cells. Neurons were identified and
voltage-clamped at -50 mV, 22 degrees C. The EPSC decayed as a single
exponential for both cell types, but the decay time constants differed
considerably; 10.2 +/- 2.3 msec (mean +/- SD) for C cells and 5.5 +/- 1.1
msec for B cells. Analysis of ACh- induced membrane current fluctuations
revealed spectra that fit single- Lorentzian functions and gave estimates
of the mean channel open time of 9.8 +/- 2.0 msec and 5.2 +/- 0.9 msec for
C and B cells, respectively. Thus, the clear difference in EPSC decay rate
for these two types of ganglion cells is most likely due to the differences
in the mean lifetimes of their synaptic channels.