EFFECTS OF AXOTOMY OR TARGET ATROPHY ON MEMBRANE-PROPERTIES OF RAT SYMPATHETIC-GANGLION CELLS

1. The electrical properties of rat superior cervical ganglion cells w ere examined in vitro with intracellular microelectrodes after axotomy or atrophy of the submandibular salivary gland. 2. Membrane time cons tant, input resistanee and excitatory synaptic potentials (EPSPs) were decreased to about 50 % of their control values 7-10 days after axoto my. 3. Axotomized ganglion cells also showed reduced action potentials and after-hyperpolarizations (AHPs). The AHP duration was reduced to 40 % of the control value. 4. In 25 % of the axotomized cells, the act ion potential was followed by an after-depolarization (ADP) instead of the AHP that was always present in control cells. In eleven out of se venteen axotomized cells with ADP, preganglionic stimulation failed to evoke an EPSP, whereas the failure of the synaptic response was never observed in control cells and occurred only in two of fifty-three axo tomized cells with AHP. 5. In some axotomized cells with AHP, a depola rizing potential developed after a train of action potentials. This wa s never observed in control cells. 6. Sympathetic neurones innervating the submandibular gland in control animals had membrane properties si milar to those observed in other ganglion cells. 7. The properties of neurones innervating the submandibular gland remained unaltered after the experimentally induced atrophy of the gland. 8. It is concluded th at the marked effects of short-term axotomy on membrane properties of sympathetic ganglion cells are not reproduced by long-term atrophy of the target tissue.