| 原 文 |
題 目 |
Spontaneous contractions evoke afferent nerve firing in mouse bladders with detrusor overactivity |
| 作 者 |
McCarthy CJ, Zabbarova IV, Brumovsky PR, Roppolo JR, Gebhart GF, Kanai AJ. |
| 出 處 |
J Urol. 2009;181(3):1459-66. |
| 出版日期 |
Mar, 2009 |
| 評 論 |
近年來急尿感和頻尿症狀都被認為和輸入神經的異常傳導有密切的關係，而輸入神經的活性又被認為與膀胱的自發性活動有關聯。因此作者們利用完整的小鼠膀胱組織（含對照組及脊髓損傷組）及支配膀胱的輸入神經來檢測膀胱自發性活動和輸入神經的關係。實驗發現，大的自發性活動確實會激發輸入神經衝動。並發現在正常的膀胱，自發性活動是由許多不同位置的啟始點開始，這些自發性活動的強度較小且頻率較高。而在脊髓損傷的膀胱，自發性活動是僅由位於一二處的啟始點所激發，這些自發性活動的強度較大及頻率較低。作者們認為，脊髓損傷會造成老鼠膀胱產生較大強度及低頻的自發性活動，而這些自發性活動會引起輸入神經的異常傳導，進而導致下泌尿道症狀。這篇文章首次直接證明了輸入神經的活性與膀胱的自發性活動有關聯，幫助科學家們對下泌尿道症狀病因的了解又向前邁進一步。
|
| abstract |
PURPOSE: Afferent nerve firing has been linked to spontaneous bladder contractions in a number of lower urinary tract pathologies and it may lead to urgency and incontinence. Using optical mapping, single unit recording and tension measurements we investigated the correlation between afferent nerve firing and spontaneous bladder contractions in spinal cord transected mice. MATERIALS AND METHODS: Bladder-nerve preparations (bladder sheets and the associated L6-S2 pelvic nerves) were dissected from normal and spinal cord transected mice showing overactivity on cystometry and opened along the ventral aspect from base to dome. Bladder sheets were mounted horizontally in a temperature regulated chamber to simultaneously record Ca(2+) transients across the mucosal surface, single unit afferent nerve firing and whole bladder tension. RESULTS: Single unit afferent fibers were identified by probing their receptive fields. Fibers showed a graded response to von Frey stimulation and a frequency of afferent firing that increased as a function of the degree of stretch. Optical maps of Ca(2+) transients in control bladders demonstrated multiple initiation sites that resulted in high frequency, low amplitude spontaneous contractions. Alternatively in maps of the bladders of spinal cord transected mice Ca(2+) transients arose from 1 or 2 focal sites, resulting in low frequency, high amplitude contractions and concomitant afferent firing. CONCLUSIONS: Large amplitude, spontaneous bladder contractions evoke afferent nerve activity, which may contribute to incontinence.
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