Afferent innervation of the guinea-pig's ureter.

The electrical activity of 41 mechanosensitive afferent units was recored using an in vitro preparation of the guinea-pig's ureter. The conduction velocities of these fibres were found to be in the C-fibre range. Only 4 of them responded to contractions of the ureter. The activation threshold of the units to intraluminal (i.l.) pressure varied between 3 and 50 mm Hg. It is concluded that some of these afferent fibres might be involved in the signalling of nociceptive events.