title: Dose-rate dependent effects of ionizing radiation on vascular reactivity.
abstract: 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 ((137)Cs, 9 x 10(-4) Gy s(-1), 18 min) and chronic ((137)Cs, 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 micromol l(-1)). Furthermore, low intensity radiation strongly diminished the vasodilator properties of NO-donor sodium nitroprusside (5 micromol 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.
authors.affiliation: Institute of Radiobiology, National Academy of Sciences of Belarus, Fedyuninskogo street 4, 246007 Gomel, Belarus.
authors.forename: T
authors.initials: T
authors.lastname: Suvorava
authors.forename: L
authors.initials: L
authors.lastname: Luksha
authors.forename: K Ya
authors.initials: KY
authors.lastname: Bulanova
authors.forename: L M
authors.initials: LM
authors.lastname: Lobanok
mesh_terms: D000818:Animals; D001011:Aorta / Q000502:physiology* / Q000528:radiation effects*; D001783:Blood Flow Velocity / Q000502:physiology* / Q000528:radiation effects; D003331:Coronary Vessels / Q000502:physiology* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D008297:Male; D011829:Radiation Dosage; D011839:Radiation, Ionizing; D051381:Rats; D014661:Vasoconstriction / Q000502:physiology* / Q000528:radiation effects*