Bladder activation: afferent mechanisms.

Research output: Contribution to journalArticle

Abstract

The major function of the lower urinary tract is to store and periodically evacuate urine from the bladder. This requires coordination of the smooth muscles of the bladder and urethra, and of the striated muscles of the outflow region and pelvic floor by a complex neural control system. Lumbosacral afferent fibers (pelvic afferents), but also afferents in the hypogastric and pudendal nerves, are of major importance for the regulation of the mechanisms for continence and micturition. In the bladder, afferent nerves have been identified suburothelially as well as in the detrusor muscle. Suburothelially, they form a plexus that lies immediately beneath the epithelial lining. This plexus is particularly dense in the bladder neck and the trigone. The most important afferents for the micturition process are myelinated Adelta-fibers and unmyelinated C-fibers. Immunocytochemical and tracing studies have revealed that numerous peptides, including substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide, enkephalins, and cholecystokinin are localized either alone, or in combination, in afferent pathways of the bladder and urethra. The receptors on these nerves include: vanilloid receptors, purinoceptors, tachykinin, and prostanoid receptors. Extracellular adenosine triphosphate (ATP) has been found to mediate excitation of small-diameter sensory neurons via P2X3 receptors, and it has been proposed that in the bladder, distention causes release of ATP from the urothelium. ATP, in turn, can activate P2X3 receptors on suburothelial afferent nerve terminals to evoke a neural discharge. However, it is most likely that a cascade of inhibitory and stimulatory transmitters/mediators, as well as ATP, are involved in the transduction mechanisms underlying the activation of afferent fibers during bladder filling.

Details

Authors
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Urology and Nephrology

Keywords

  • Afferent Pathways : physiology, Adenosine Triphosphate : physiology, Animal, Bladder : innervation, Bladder : physiology, Human, Nerve Fibers : physiology, Nerve Fibers, Myelinated : physiology, Neurotransmitters : physiology, Receptors, Drug : physiology, Prostaglandin : physiology, Purinergic : physiology, Purinergic P2 : physiology, Tachykinin : physiology, Urination : physiology
Original languageEnglish
Pages (from-to)43-50
JournalUrology
Volume59
Issue number5 Suppl 1
Publication statusPublished - 2002
Publication categoryResearch
Peer-reviewedYes