The effects of bradykinin on afferent units in intra-abdominal sympathetic nerve trunks

The effects of intra-arterial injections of bradykinin on afferent discharges in the splanchnic and hypogastric nerves have been studied. All units which were excited by the peptide were mechanosensitive. Following i.a. bradykinin, the slowly adapting mechanoreceptors associated with the bladder showed increased discharge rates which appear to be related to changes in intravesical pressure. When the effects of bradykinin on the bladder were blocked by cord cooling, the afferents were not excited. It is concluded that bradykinin causes discharges in the slowly adapting mechanoreceptors around the bladder because it causes bladder contractions, and not because of any chemosensitivity of the nerve ending.