Physiologic and Pathophysiologic Functions of Purinoceptors in Voiding Reflex.

Abstract

Purinergic neurotransmission has been regarded as major component of non-adrenergic, noncholinergic (NANC) contraction in detrusor smooth muscle. Although in normal human detrusor, this contraction seems to be small, the importance of the NANC component for detrusor contraction in disease conditions such as detrusor overactivity remains to be established. Based on many evidences for purinergic contributions in lower urinary tract, ATP and purinoceptors has been suggested to be involved in both efferent and afferent mechanism in voiding reflex. ATP signaling via P2X1 receptors plays an important role in efferent neural control of urinary bladder function, although to varying degrees across species from experimental animals to men. The efferent function of purinoceptors may be enhanced in detrusor overactivity and aging. ATP also suggested being involved in mechanosensory transmission, via activation of P2X3 and P2X2/3 receptors on sensory afferent nerves. The afferent function of purinoceptors may be related with pathophysiology of overactive bladder or interstitial cystitis, mediating bladder hyperexicitability. These results suggest that the selective antagonists for the purinoceptors may offer better relief of sensory and motor symptoms for overactive bladder or interstitial cystitis patients in the future. (J Korean Continence Soc 2008;12:93-8)