The development of the cardiovascular pathology and vascular changes may be caused by ionizing irradiation (II). The aim of our work was to study the changes of the vessels reactivity in adult and old rats to the action of II. It has been shown in the experiments on the isolated segments of the thoracic aorta of the adult and old Wistar male rats that 1 month later after a single II (3 Gr) the old animals had the following changes: weakening of the endothelium-dependent vasodilatation response to acetylcholine, increasing the vessels sensitivity to endothelium-independent vasodilatator the sodium nitroprusside, vascular relaxing reaction to insulin was unchanged and vasoconstriction reaction to epinephrine decreased.
