Effects of Lead Ions on the Synaptic Responses of Neurons of the Rat Sympathetic Ganglion

Abstract

Using intracellular recording, we studied the effects of lead ions on the synaptic responses of neurons of the superior cervical ganglion (SCG) of the rat. Three groups of SCG neurons were found; they differed from each other in directions of the changes evoked by Pb2+ applications and in their sensitivity to this agent. In two groups of the phasic SCG neurons, Pb2+ decreased the amplitude of EPSP evoked by stimulation of the cervical sympathetic nerve with EC50 of (2.2 ± 0.2) · 10-6 M and (3.55 ± 0.29) · 10-5 M, respectively. In the tonic neurons, 2 · 10-6 M Pb2+ increased the EPSP amplitude by 27 ± 2%, on average, as compared with the control values. We postulate that the specificity of responses of these three groups of SCG neurons to the action of Pb2+ is determined by the different subunit composition of the nicotinic cholinoreceptors in the membrane of these cells.