Intracellular recordings from the stellate ganglion of the cat.

1. Intracellular recordings were made, in vitro, and in situ, from neurones of the cat stellate ganglion. 2. Preganglionic stimulation, in vitro, via the T3 ramus or post-ganglionic stimulation via the ventral ansa, dorsal ansa or stellate cardiac nerve evoked graded synaptic responses which led to the discharge of one or more action potentials. Since the conduction velocities of fibres converging onto a single cell may vary, their convergence may mean that there is an interaction in the stellate ganglion between functionally different pathways. 3. Most neurones in the stellate ganglion receive synaptic input from fibres of both central and peripheral origin. 4. Intracellular recordings were made, in situ, from neurones of the cat stellate ganglion attached via the stellate cardiac nerve to the rest of the animal. When peripheral sympathetic afferent input to the stellate ganglion was increased by occluding the descending aorta, some of the neurones exhibited an increase in excitatory post-synaptic potentials (e.p.s.p.s) and/or action potentials. Most of the synaptic input recorded from the ganglion cells in situ had a close relationship with the cardiac cycle and/or respiration. 5. These data and our previous studies support the contention that sympathetic efferent nerve activity can be modified by peripheral excitatory inputs and that these neural connexions may function as pathways for a peripheral reflex at the level of the paravertebral ganglion.