C nociceptor activity in XXXX nerve during painful and non painful skin stimulation.

@entity1 @entity477 @entity158
Percutaneous recordings from more than one hundred single C fibres have been performed in the radial nerve of conscious @entity1 subjects. All these fibres belong to the poly-modal C nociceptor group, being excited by mechanical and thermal and also by chemical stimulation. Conduction velocities showed a monophasic distribution with a mean value of 0.86 m/s (SD: 0.17). The mechanical threshold, measured with von Frey hairs, varied between 2.3 and 13.1 g. The receptive field was circular or elliptical; for 33 units the mean axes were 6 mm and 7 mm. Mechanically evoked C fibre discharge even up to more than 10 spikes/s was not necessarily accompanied by @entity158 sensation. Nettle sting evoked an irregular C fibre discharge (maximum 10 spikes/s) accompanied by a pricking and burning sensation; the sensation of itch which was sometimes reported, was not correlated with the discharge frequency. C fibre activation by a chemical irritant (paint remover) also evoked an irregular discharge (maximum 3 to 6 spikes/s), accompanied by pricking and burning @entity158 sensation. The C threshold for radiant heat usually lay below the subject's @entity158 threshold. Increasing skin temperature produced increasing neural firing rate. The mean spike frequency rarely exceeded two spikes/s even with stimuli evoking strong @entity158 . The occurrence of subjective @entity158 response could be as well predicted from th C fibre spike frequency as from the skin temperature. It is concluded that nociceptive C input provoked by thermal or chemical stimuli correlates well with @entity158 sensation. However, similar C input provided by mechanical stimulation which activates also @entity477 mechanoreceptors, did not necessarily produce @entity158 sensation.
