The application of irritant chemicals selectively to the skin of the leech ganglion/body wall preparation.

A technique is described for applying chemical irritants selectively to the skin of a superfused ganglion/body wall preparation of the horse leech, Haemopis sanguisuga. Details are given of the intracellular recording from sensory neurones of the effects of the irritant dibenzoxazepine and of mechanical stimulation. Dibenzoxazepine produced changes in the spontaneous firing pattern in the nociceptive cells of the leech but did not affect the response to mechanical stimulation of the skin in any type of sensory cell. It is possible that the system described could be used as a model of cutaneous excitation evoked by drugs or mechanical stimulation in higher animals.