NORADRENALINE-MEDIATED LATERAL INHIBITION IN THE SYMPATHETIC-GANGLION

Intracellular recordings were made from neurons of denervated superior cervical ganglion (SCG) of the rat. Focal electrical stimulation near the recording site evoked a monosynaptic inhibitory postsynaptic pote ntial (IPSP) in about 15% of SCG neurons. The IPSP was reversibly abol ished by alpha(2)-adrenoceptor antagonist, yohimbine. The ionic mechan ism of the IPSP appeared to be due to an increase of potassium conduct ance following the activation of alpha(2)-adrenoceptor. Electron micro scopic observations confirmed that these cells received synapses of in trinsic type. It was concluded that some SCG neurons were under an inh ibitory control from neighboring neurons via noradrenergic synapses. ( C) 1997 Elsevier Science Ireland Ltd.