Radiation Protection Dosimetry Advance Access originally published online on November 28, 2006
Radiation Protection Dosimetry 2006 122(1-4):543-545; doi:10.1093/rpd/ncl432
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Dose-rate dependent effects of ionizing radiation on vascular reactivity
1 Institute of Radiobiology, National Academy of Sciences of Belarus, Fedyuninskogo street 4, 246007 Gomel, Belarus
2 Belarusian State Medical University, Physiology Department, Dzerzhinskogo street 83, 220116 Minsk, Belarus
3 International Sakharov Environmental University, Research Institute of Ecological Problems, Dolgobrodskaya street 23, 220009 Minsk, Belarus
* Corresponding author: Prof.Lobanok{at}tut.by
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Abstract |
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This study was designed to investigate the dose-rate dependent effects of ionising radiation on endothelium- and NO-mediated reactivity of aorta and coronary vessels. Rats were exposed to acute (137Cs, 9 x 10–4 Gy s–1, 18 min) and chronic (137Cs, 2.8 x 10–7 Gy s–1, 41 days) radiation in 1 Gy dose. Acute irradiation transiently increased coronary flow in eNOS-activity-dependent manner on day 3 after exposure. In striking contrast, chronic irradiation caused a significant depression of coronary flow even on day 90 after irradiation and abolished the effects of NO-synthase inhibitor N-nitro-L-arginine methyl ester (10 µmol l–1). Furthermore, low intensity radiation strongly diminished the vasodilator properties of NO-donor sodium nitroprusside (5 µmol l–1). A similar pattern was observed in aortic rings. Endothelium-dependent vasodilation was increased on days 3 and 10 after acute irradiation, but strongly inhibited following chronic exposure for the entire post-radiation period. This was accompanied by a diminished vasodilator response to NO-donor on days 3, 10 and 30 of post-radiation but not on day 90. The data suggest that ionising radiation in 1 Gy induces changes of aortic and coronary vessels reactivity depending on the dose-rate and the interval after exposure.