Document Detail

The effects of exogenous amino acids on the relaxant responses of pig urethral smooth muscle evoked by stimulation of the inhibitory nitrergic nerves.
MedLine Citation:
PMID:  15480748     Owner:  NLM     Status:  MEDLINE    
Inhibitory innervation of urethral smooth muscle is mediated partly through release of NO. We investigated the mechanisms involved in the supply of the substrate L: -arginine to NO synthase by examining the relaxant response of the muscle to electrical field stimulation (EFS) and the effects of addition of amino acids to the bathing medium. Relaxant responses persisted during hours of repetitive stimulation but were enhanced rapidly by addition of L: -arginine (the "arginine paradox"). Addition of L: -lysine (competes with L: -arginine for transport on the y(+) carrier) and L: -glutamine (competing on the y(+)L carrier) attenuated the enhancement. Enhancement persisted after washing but was reversed by application of L: -lysine, suggesting that exogenous L: -arginine fills an intracellular pool and that L: -lysine can trans-stimulate its efflux from the pool. After prolonged depolarization in high-K(+), Na(+)-free solution the relaxant response became purely nitrergic. Addition of L: -arginine during the exposure continued to enhance the subsequent responses but L: -glutamine added with L: -arginine, could no longer reduce this enhancement. The results show the arginine paradox in inhibitory nerves and suggest the involvement of y(+) and y(+)L carriers in the transport of L: -arginine.
N Tugba Durlu; Alison F Brading
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Publication Detail:
Type:  In Vitro; Journal Article     Date:  2004-10-05
Journal Detail:
Title:  Pflügers Archiv : European journal of physiology     Volume:  449     ISSN:  0031-6768     ISO Abbreviation:  Pflugers Arch.     Publication Date:  2005 Jan 
Date Detail:
Created Date:  2005-02-28     Completed Date:  2005-05-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0154720     Medline TA:  Pflugers Arch     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  413-21     Citation Subset:  IM    
Faculty of Pharmacy, Department of Pharmacology, Hacettepe University, 06100 Sýhhiye, Ankara, Turkey.
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MeSH Terms
Amino Acids / pharmacology*
Arginine / metabolism,  pharmacology
Electric Stimulation
Enzyme Inhibitors / pharmacology
Lysine / pharmacology
Muscle Relaxation / drug effects
Muscle, Smooth / drug effects*
Nitric Oxide / physiology*
Nitric Oxide Synthase / antagonists & inhibitors
Nitric Oxide Synthase Type III
Nitroarginine / pharmacology
Synaptic Transmission / physiology
Urethra / drug effects*
Reg. No./Substance:
0/Amino Acids; 0/Enzyme Inhibitors; 10102-43-9/Nitric Oxide; 2149-70-4/Nitroarginine; 56-87-1/Lysine; 74-79-3/Arginine; EC Oxide Synthase; EC Oxide Synthase Type III

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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