Improvement of bladder storage function by α1‐blocker depends on the suppression of C‐fiber afferent activity in rats

Neurourology and Urodynamics - Tập 25 Số 5 - Trang 461-467 - 2006
Osamu Yokoyama1, Anwar Yusup1, Nobuyuki Oyama1, Yoshitaka Aoki1, Kazuya Tanase1, Yosuke Matsuta1, Yoshiji Miwa1, Hironobu Akino1
1Department of Urology, Faculty of Medical Science, University of Fukui, Fukui, Japan

Tóm tắt

AbstractAimsα1‐blockers improve voiding symptoms through the reduction of prostatic and urethral smooth muscle tone; however, the underlying mechanism of improvement of storage symptoms is not known. Using a rat model of detrusor overactivity caused by cerebral infarction (CI), we undertook the present study to determine whether the effect of an α1‐blocker, naftopidil, is dependent on the suppression of C‐fiber afferents.MethodsTo induce desensitization of C‐fiber bladder afferents, we injected resiniferatoxin (0.3 mg/kg, RTX) sub‐cutaneously to female Sprague‐Dawley rats 2 days prior to left middle cerebral artery occlusion (MCAO) (RTX‐CI rats). As controls we used rats without RTX treatment (CI rats). MCAO and insertion of a polyethylene catheter through the bladder dome were performed under halothane anesthesia. We investigated the effects on cystometrography (CMG) of intravenous (i.v.), intracerebroventricular (i.c.v.), or intrathecal (i.t.) administration of naftopidil in conscious CI rats.ResultsBladder capacity (BC) was markedly reduced after MCAO in both RTX‐CI and CI rats. I.v. administration of naftopidil significantly increased BC in CI rats without an increase in residual volume, but it had no effects on BC in RTX‐CI rats. I.t. administration of naftopidil significantly increased BC in CI but not in RTX‐CI rats.ConclusionsThese results suggest that naftopidil has an inhibitory effect on C‐fiber afferents in the lumbosacral spinal cord, improving BC during the storage phase. Neurourol. Urodynam. © 2006 Wiley‐Liss, Inc.

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Neurourology and Urodynamics

Tập 25 Số 5

461-467

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