Demonstration of the synaptic origin of primary afferent depolarization (PAD) in the isolated spinal cord of the hamster

Abstract

Intracellular recordings have been made from 31 primary afferent fibres within the dorsal horn of an isolated mammalian spinal cord. In 17 fibres stimulation of an adjacent dorsal root evoked primary afferent depolarization (PAD); these fibres also showed spontaneous depolarizations. Replacement of the calcium in the perfusing medium by manganese blocked both evoked and spontaneous activity showing them to be of synaptic origin. Observations on the effects of current injection and of bicuculline support an involvement of GABA in the generation of PAD.