Fig. 2.

Schematic representation of the experimental apparatus. The experimental apparatus consisted of a superfusion system with a main and ancillary reservoir (of HEPES-buffered Tyrode's at 37 °C) feeding into an isolated polyvinylchloride tube, via a three-way tap. A freshly dissected SLN was partially placed in the lumen of the tubing and this was further immersed in filtered, HEPES-buffered Tyrode's at 37 °C held in a jacketed organ bath. The $P_{{\text{O}}_2}$ of the main reservoir could be modulated by rotameters connected to oxygen and nitrogen cylinders. The ancillary reservoir was used to deliver the CN challenges and the cytokines (IL-1β or TNF-α at concentrations of 0.5 ng/ml, 5 ng/ml or 50 ng/ml). The SLN action potentials were detected by way of a glass suction electrode, digitised and analysed by spike recognition software. The lower panel illustrates the method by which 3 individual units are discriminated by the software – based on amplitude and shape.