[DYNAMICS OF NITROGEN OXIDE METABOLITES IN THE PLASMA AND ASCITES DURING ZAJDEL HEPATOMA GROWTH IN VIVO]

The dynamics of extracellular nitrogen oxide metabolites localized in the plasma and ascites during Zajdel ascites hepatoma growth in the abdominal cavity has been investigated. An increase in peroxynitrite concentration was found by the levels of nitrotyrosine (up to 10-11 nM) in blood plasma at the initial stage of tumor cell development. In the course of further tumor development, an oxidative stress developed, which might cause oxidation of protein components including tyrosine. All these processes may cause a decrease in the accessible amount of tyrosine for nitration and lead to a fall in nitrotyrosine level (to 3-6 nM) at the final stages of tumor growth. Nitrotyrosine dynamics in the region of tumor growth is essentially analogous to that in the plasma because proteins during tumor growth cames from the blood plasma of tumor bearer. In studying the dynamics of nitrosylation of sulfur-bearing protein groups, an increase in the concentration of S-nitrosothyols was found to occur in the blood plasma for up to 6 days of the experiment, subsequently their concentration decreased. In the ascites, where protein R-SNO arrives, the mean concentration of nitrosothyols upon tumor growth is lower compared to that of the plasma. In studying the dynamics of final stable nitrogen oxide decay products--nitrites/nitrates, it has been found that during tumor development the concentration of these metabolites in the plasma varies only moderately within some range and sharply increases at the final stage of the experiment. In the area of tumor growth, an analogous trend in the behavior of nitrites/nitriaes has been registered (noted, marked), but with a higher background level, which might be due to both the functioning of immunocompetent cells, microphages in particular, and a decreased rate of utilization of substances from the ascites. Based on the aforesaid, it has been concluded that the nitrosylating stress in the organism of the bearer of a tumor is being developed along with the oxidative stress.