Bladder activation: Afferent mechanisms
Bladder activation: Afferent mechanisms
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DOI：
10.1016/s0090-4295(01)01637-5
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发表时间：
2002-05-01
期刊：
影响因子：
2.1
通讯作者：
Andersson, KE
中科院分区：
文献类型：
--
作者：
Andersson, KE
下尿路的主要功能是储存和定期从膀胱排出尿液。这需要通过复杂的神经控制系统协调膀胱和尿道的平滑肌以及流出区和骨盆底的横纹肌。腰骶传入纤维（骨盆传入纤维）以及腹下神经和阴部神经的传入纤维对于调节排尿和排尿机制具有重要意义。在膀胱中，传入神经已被确定在尿道下以及在逼尿肌。在皮下，它们形成一个位于上皮衬里下面的丛。该神经丛在膀胱颈和膀胱三角区尤其密集。排尿过程中最重要的传入纤维是有髓Adelta纤维和无髓C纤维。免疫细胞化学和示踪研究表明，许多肽，包括物质R降钙素基因相关肽，血管活性肠多肽，脑啡肽，胆囊收缩素是本地化单独或组合，在传入途径的膀胱和尿道。这些神经上的受体包括：香草素受体、嘌呤受体、速激肽和前列腺素受体。细胞外三磷酸腺苷（ATP）已被发现通过P2 X（3）受体介导小直径感觉神经元的兴奋，并且已经提出在膀胱中，膨胀导致ATP从尿道释放。ATP反过来又可以激活上皮下传入神经末梢上的P2 X（3）受体，引起神经放电。然而，最有可能的是，抑制性和刺激性递质/介质以及ATP的级联参与膀胱充盈期间传入纤维激活的转导机制。
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 R 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 P2X(3) receptors, and it has been proposed that in the bladder, distention causes release of ATP from the urothelium. ATP, in turn, can activate P2X(3) 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.