Document Detail

The shaping of nitric oxide signals by a cellular sink.
MedLine Citation:
PMID:  11691877     Owner:  NLM     Status:  MEDLINE    
1. The functioning of nitric oxide (NO) as a biological messenger necessitates that there be an inactivation mechanism. Cell suspensions from a rat brain region rich in the NO signalling pathway (cerebellum) were used to investigate the existence of such a mechanism and to determine its properties. 2. The cells consumed NO in a manner that could not be explained by reaction with O(2), superoxide ions or contaminating red blood cells. Functionally, the mechanism was able to convert constant rates of NO formation into low steady-state NO concentrations. For example, with NO produced at 90 nM min(-1), the cells (20 x 10(6) ml(-1)) held NO at 20 nM. Various other cell types behaved similarly. 3. The influence of NO inactivation on the ability of NO to access its receptor, soluble guanylyl cyclase, was explored by measuring cGMP accumulation in response to the clamped NO concentrations. The extrapolated steady-state EC(50) for NO was 2 nM, a concentration readily achieved by low NO release rates, despite inactivation. 4. When confronted by higher NO release rates for several minutes, the clamping mechanism failed, resulting in a progressive rise in NO concentration. While the clamp was maintained, cellular respiration was unaffected but, as it failed, respiration became inhibited by NO. The IC(50) was measured to be 120 nM (at 100-140 microM O(2)). 5. It is concluded that cerebellar (and other) cells possess a powerful NO inactivation mechanism that, extrapolated to the whole tissue, would impose on NO a half-life of around 100 ms. This and other properties of the device appear ideal for shaping low-level NO signals for activating its receptor, soluble guanylyl cyclase, whilst avoiding adverse effects on mitochondrial function. The exhaustibility of the mechanism provides a scenario for NO to become toxic.
C Griffiths; J Garthwaite
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  536     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  2001 Nov 
Date Detail:
Created Date:  2001-11-05     Completed Date:  2002-01-11     Revised Date:  2013-06-09    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  855-62     Citation Subset:  IM    
The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK.
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MeSH Terms
Brain / cytology*,  physiology*
Cerebellum / cytology,  physiology
Electric Stimulation
Erythrocytes / physiology
Guanylate Cyclase / physiology
Membrane Potentials / physiology
Mitochondria / metabolism
Nitric Oxide / physiology*
Oxygen Consumption / physiology
Patch-Clamp Techniques
Rats, Wistar
Signal Transduction / physiology*
Reg. No./Substance:
10102-43-9/Nitric Oxide; EC Cyclase

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