Evidence to support the peripheral branching of primary afferent C-fibres in the rat: an in vitro intracellular electrophysiological study

Intracellular voltage recordings were made in vitro at 36.5 ± 1°C from 35 rat lumbar dorsal root ganglion (DRG) neurones with a peripheral conduction velocity (CV) in the C-fibre range (0.3-2.2 m/s). The peripheral nerve (PN) was stimulated in one of three different ways, each delivering single stimuli (0.1-1 ms duration, 2-3-times threshold; maximum 50 V) at a low frequency (0.3 Hz). With each of the three stimulation methods used here a similar proportion of cells (approximately 30%) showed changes, either an abrupt latency change or a soma invasion by two action potentials (APs). Both of these changes were consistent with branching of primary afferent C-fibres in the PN.