<p>Background. System of nitric oxide (NO), which consists of NO, and its metabolites, is very important for<br />various biological processes. NO is signalling molecules and mediators of intracellular and intercellular interaction<br />that causes relaxation of smooth muscles of blood vessel walls, inhibits platelet aggregation and their adherence,<br />is involved in the transmission of nerve impulses, cell proliferation.<br />Objective. The aim of our research was to study the content of nitric oxide metabolites in blood serum and<br />bronchoalveolar lavage, to substantiate their role in pathogenesis of hepatopulmonary syndrome in<br />experiment.<br />Methods. The experiments were performed on 56 outbread male rats, 180-220 g in weight. The first experimental<br />model of hepatopulmonary syndrome (HPS) was made by imposition of double ligature on common<br />bile duct and its further dissection with a scalpel. The second experimental HPS model was made by 8-week intragastric<br />administration of oil solution CCl4 (400 g per 1 L), 0.5 ml per 100 g of body weight on the first day of<br />the experiment, 0.3 ml per 100 g on the third day of the experiment and then every third day until the end of the<br />experiment 0.3 ml per 100 g. A mixture of corn flour, lard and cholesterol and alcohol solution was added to the<br />standard diet of the rats.<br />Results. The total content of nitric oxide metabolites in blood serum of the rats of the experimental group<br />No.1 (on the 31st day after the common bile duct ligation) was significantly increased in 3.9 times (p1<0,001) if<br />compared with the control group №1. In the rats of the 2nd experimental group (with carbon tetrachloride induced<br />cirrhosis) the total content of nitric oxide metabolites in blood serum also significantly increased in 3.1 times<br />(p1<0,001). Comparison of nitric oxide metabolites content in blood serum and bronchoalveolar lavage, which<br />directly indicated about the processes in lung tissue, was great importance.<br />Conclusions. So, in rats with experimental hepatopulmonary syndrome activation of nitroxydergic process<br />by significant increase in nitric oxide metabolites in blood serum and bronchoalveolar lavage took place.<br />KEYWORDS: hepatopulmonary syndrome, nitric oxide metabolites.</p>