Intracellular recordings from lateral horn cells fo the spinal cord in vitro.

Intracellular recording was used in studies of the preganglionic neurons of the autonomic nervous system. These were carried out on isolated segments of the cat spinal cord. It was found that the lateral horn cells have electrical membrane characteristics similar to postganglionic neurons, but many of them have a much longer afterhyperpolarization. 5-Hydroxytryptamine, noradrenaline and aspartate induce depolarizations in lateral horn cells which are characteristically associated with an increased membrane resistance. EPSPs in lateral horn cells are not cholinergic in nature, though many cells are endowed with excitatory nicotinic receptors. Some interneurons also appear to have excitatory muscarinic receptors. Glutamate can depolarize many lateral horn cells. This excitatory amine does not seem to be responsible for the production of an EPSP, since the EPSP persisted during the continued presence of glutamate in the superfusing medium. All the neurons examined in the lateral horn are susceptible to the hyperpolarizing and shunting actions of GABA and glycine. In a small group of neurons, noradrenaline caused a hyperpolarization.