Electrophysiological studies of new-born rat nodose neurones in cell culture.

1. Neurones of the nodose ganglion of the vagus nerve were dissociated from new-born rats and grown in the virtual absence of non-neuronal cells and in the presence of nerve growth factor. 2. The resting potentials of the neurones ranged from -40 to -80 mV. Action potentials were of short duration, with no inflexion on the falling phase; others were of longer duration with a hump on the falling phase. 3. The inward current of the action potential was carried either predominantly by Na+ or by Na+ and Ca2+. 4. Tetrodotoxin (1 microM) blocked the Na+ channels of some neurones but in other neurones the Na+ channels were partially or completely resistant to tetrodotoxin (1-10 microM). 5. Many neurones formed excitatory synapses on neighbouring neurones which were blocked or greatly reduced by conventional ganglionic nicotinic antagonists. This indicates that these neurones secreted ACh and expressed ACh receptors at these synapses. 6. The accompanying paper (Baccaglini & Cooper, 1981) reports the effect of co-culturing nodose neurones with non-neuronal cells on the expression of functional nicotinic receptors.