Document Detail


Gamma irradiation induces acetylcholine-evoked, endothelium-independent relaxation and activates K-channels of isolated pulmonary artery of rats.
MedLine Citation:
PMID:  15590185     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: To test the effects of irradiation (R*) on the pulmonary artery (PA). METHODS AND MATERIALS: Isolated PA rings were submitted to gamma irradiation (cesium, 8 Gy/min(-1)) at doses of 20 Gy-140 Gy. Rings were placed in an organ chamber, contracted with serotonin (10(-4) M 5-hydroxytryptamine [5-HT]), then exposed to acetylcholine (ACh) in incremental concentrations. Smooth muscle cell (SMC) membrane potential was measured with microelectrodes. RESULTS: A high dose of irradiation (60 Gy) increased 5HT contraction by 20%, whereas lower (20 Gy) doses slightly decreased it compared with control. In the absence of the endothelium, 5-HT precontracted rings exposed to 20 Gy irradiation developed a dose-dependent relaxation induced by acetylcholine (EI-ACh) with maximal relaxation of 60 +/- 17% (n = 13). This was totally blocked by L-NAME (10(-4) M), partly by 7-nitro indazole; it was abolished by hypoxia and iberiotoxin, decreased by tetra-ethyl-ammonium, and not affected by free radical scavengers. In irradiated rings, hypoxia induced a slight contraction which was never observed in control rings. No differences in SMC membrane potential were observed between irradiated and nonirradiated PA rings. CONCLUSION: Irradiation mediates endothelium independent relaxation by a mechanism involving the nitric oxide pathway and K-channels.
Authors:
Veronique Eder; Mathieu Gautier; Julien Boissière; Catherine Girardin; Manuel Rebocho; Pierre Bonnet
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  International journal of radiation oncology, biology, physics     Volume:  60     ISSN:  0360-3016     ISO Abbreviation:  Int. J. Radiat. Oncol. Biol. Phys.     Publication Date:  2004 Dec 
Date Detail:
Created Date:  2004-12-13     Completed Date:  2005-01-10     Revised Date:  2005-11-17    
Medline Journal Info:
Nlm Unique ID:  7603616     Medline TA:  Int J Radiat Oncol Biol Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1530-7     Citation Subset:  IM    
Affiliation:
Laboratoire de Physiopathologie de la Paroi Artérielle, Faculté de Médecine, Université François Rabelais, Tours, France. eder@med.univ-tours.fr
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MeSH Terms
Descriptor/Qualifier:
Acetylcholine / pharmacology*
Animals
Cesium
Endothelium, Vascular / drug effects,  radiation effects*
Enzyme Inhibitors / pharmacology
Gamma Rays*
Muscle, Smooth, Vascular / drug effects,  radiation effects
Nitric Oxide Synthase / antagonists & inhibitors
Potassium Channels / physiology,  radiation effects*
Pulmonary Artery / drug effects,  radiation effects*
Rats
Serotonin / pharmacology
Vasoconstriction / drug effects,  radiation effects
Vasodilation*
Chemical
Reg. No./Substance:
0/Enzyme Inhibitors; 0/Potassium Channels; 50-67-9/Serotonin; 51-84-3/Acetylcholine; 7440-46-2/Cesium; EC 1.14.13.39/Nitric Oxide Synthase

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