Evidence for the involvement of a capsaicin-sensitive innervation in the afferent branch of micturition reflex in rats.

Functional evidence is presented indicating the presence in the rat urinary bladder of a capsaicin-sensitive innervation which is involved in regulating micturition threshold. Endogenous substance P and/or related tachykinins appear to be present in the capsaicin-sensitive nerve endings of the rat bladder and may play a neurotransmitter role in relaying information concerned with bladder volume from the detrusor muscle to the central nervous system. In addition, neurotransmitter release from the peripheral ending of the capsaicin-sensitive fibers may play an efferent role in certain motor and/vascular responses at bladder muscle level.