Age related features of postradiation changes of functional activity of local vascular renin-angiotensin system

The postradiation changes of constriction effects of angiotensin II (Ang II) and angiotensin I (Ang I) on isolated preparations of thoracic aorta young and old rats which underwent gamma-irradiation in dose 1 Gy (137Cs, 9 x 10(-4) Gy/s) were investigated. It has been found, that the aging leads to the alteration of angiotensin receptors, which appears as changes in their density and/or sensitivity to action of agonist. With increase of age the activity of angiotensin-converting enzyme (ACE) in the wall of aorta is oppressed, and as a result, the level of local formation of Ang II and the constriction, caused by it are reduced. The inhibitory influence of endothelium on vasoconstriction effects of Ang II and Ang I in ontogenesis does not change. The influence of gamma-radiation in a dose of 1 Gy modifies the functional activity of the local vascular renin-angiotensin system (RAS): the sensitivity and/or density of angiotensin receptors and the activity of ACE increased the dilatation influences of endothelium were oppressed mainly for account of easing the synthesis of NO. The duration of postradiation infringements of functional activity of local vascular RAS in many respects are determined by the stage of ontogenic development of irradiated organism.