Gamma irradiation induces acetylcholine-evoked, endothelium-independent relaxation and activates K-channels of isolated pulmonary artery of rats.
Int J Radiat Oncol Biol Phys
; 60(5): 1530-7, 2004 Dec 01.
Article
em En
| MEDLINE
| ID: mdl-15590185
ABSTRACT
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.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Artéria Pulmonar
/
Vasodilatação
/
Endotélio Vascular
/
Canais de Potássio
/
Acetilcolina
/
Raios gama
Limite:
Animals
Idioma:
En
Revista:
Int J Radiat Oncol Biol Phys
Ano de publicação:
2004
Tipo de documento:
Article
País de afiliação:
França