Activation of pelvic afferent nerves from the rat bladder during filling.

This short paper has reviewed current information on the physiology of bladder mechanoreceptors. Afferents in the bladder mucosa appear to be sensitive to distension but not to contraction of the viscus, and are also sensitive to the chemical composition of the bladder contents. Evidence is provided that suggest that Neurokinin A is released from primary afferent endings in the submucosa and is involved in both the normal response to distension, and the sensitization process. The results suggest that the low threshold mechanoreceptors are polymodal, and are modulated by various mediators, including some peptides that may originate from the sensory endings themselves, and that these mediators may be active during normal filling.