Document Detail

Exogenously administered opioids contract the female rat intrinsic urethral sphincter in vivo.
MedLine Citation:
PMID:  19899147     Owner:  NLM     Status:  MEDLINE    
BACKGROUND AND OBJECTIVE: Previous studies have reported immunoreactive opioid nerve fibers in the detrusor and lower urinary tract sphincters. However, there is a paucity of in vivo studies demonstrating the direct effect of endogenous opioids in these structures. In the present study, we investigated the contractile actions of intra-arterially administered exogenous Dynorphin-A, Met-enkephalin, Leu-enkephalin, morphine, and the opioid antagonist naltrexone on the female rat intrinsic urethral sphincter in vivo.
METHODS: Intraurethral pressure was recorded by a catheter placed at the maximum pressure zone of the intrinsic urethral sphincter in anesthetized female Sprague-Dawley rats. The effects of different opioids were studied and expressed as means and as percentages of pressure change (cmH(2)O) of the baseline intraurethral pressure.
RESULTS: Dynorphin-A, Met-enkephalin, and Leu-enkephalin evoked rapid, long-lasting contractile effects on the female rat urethra. The greatest intraurethral pressure increase was evoked by Dynorphin-A (89.2 +/- 15.3%). For Met-enkephalin, intraurethral pressure increased by 70.2 +/- 21.8% and for Leu-enkephalin, the pressure increase was 60.6 +/- 20%. Morphine, however, evoked inconsistent intraurethral pressure changes, increasing the urethral pressure in three subjects and lowering the pressure in the remaining six subjects. The opioid antagonist naltrexone reduced the intraurethral pressure by a mean of -19.0 +/- 5.8%.
CONCLUSION: Results of the present study suggest that endogenous opioids by their contractile action on the intrinsic urethral sphincter may play a role in the control of continence in rats, additional to cholinergic and noradrenergic pathways.
Robert Crayton; Wolfgang Soller; Anders Mattiasson; Agnieszka Bossowska; Tomasz Borkowski; Mariusz Majewski; Piotr Radziszewski
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Neurourology and urodynamics     Volume:  29     ISSN:  1520-6777     ISO Abbreviation:  Neurourol. Urodyn.     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-07-01     Completed Date:  2010-12-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8303326     Medline TA:  Neurourol Urodyn     Country:  United States    
Other Details:
Languages:  eng     Pagination:  777-82     Citation Subset:  IM    
Copyright Information:
(c) 2010 Wiley-Liss, Inc.
Department of Clinical and Experimental Physiology, Medical University of Warsaw, Warsaw, Poland.
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MeSH Terms
Analgesics, Opioid / pharmacology*
Muscle Contraction / drug effects*
Rats, Sprague-Dawley
Urethra / drug effects*,  physiology*
Reg. No./Substance:
0/Analgesics, Opioid

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