A controlled randomized investigation on the experimental model of contrast-agent (iopromide) induced nephropathy (ÑIN) in male rats showed that combined hydratation therapy with NAD + containing cytoprotective and anti-ischemic drug nadcin leads to decrease in the creatinine level and blood urea nitrogen (BUN) in plasma in 72 h after CIN reproduction. A linear positive strong correlation between endothelin (ET-1) level and O 2 generation (r = 0.78, p < 0.001) was observed, while no coupling was found between the production of hydrogen peroxide and ET-1 level (r = 0.13, NS), and also between the ET-1 level and catalase activity (r = 0.41, NS). In contrast to the hydration treatment, the inclusion of nadcin in therapy leads to normalization of the level of ET-1 and ET-1/creatinine ratio in blood, redox-potential NAD/NADH and NADP/NADPH in blood and kidney, inhibits the hyperproduction of free radicals, and activates the blood and renal antioxidant defense systems. Determination of the content of ET-1, ET-1/creatinine ratio, and redox-potential in plasma is recommended for use as early markers of a higher risk of renal dysfunction development during the administration of x-ray contrast agents.