RT Journal Article ID 0291ce2737aa9883 A1 Akopova, Olga V. A1 Korkach, Yulia P. A1 Kotsuruba, Anatoliy V. A1 Kolchinskaya, Lyudmila I. A1 Sagach, Vadim F. T1 Reactive Nitrogen and Oxygen Species Metabolism in Rat Heart Mitochondria under Administration of Nitric Oxide Donor in Vivo JF International Journal of Physiology and Pathophysiology JO IJPP YR 2012 FD 2013-01-23 VO 3 IS 4 SP 327 OP 340 K1 reactive nitrogen and oxygen species K1 nitroglycerin K1 calcium K1 mitochondrial permeability transition pore K1 heart mitochondria AB Some aspects of reactive nitrogen and oxygen species (RNS and ROS, respectively) metabolism in rat heart mitochondria under administration of different doses of nitroglycerin (NG) have been analyzed. It was shown that NG administration resulted in a dose-dependent increase in calcium capacity of the mitochondria, due to an inhibition of the mitochondrial permeability transition pore (MPTP) in vivo, which correlated with an activation of calcium-dependent mitochondrial NO-synthase (NOS). Larger NG doses evoked NOS activity enhancement in accord with an increase in mitochondrial calcium capacity. A dose-dependent activation of nitrate reductase was also observed. However, the amount of generated nitrite anion (NO2) decreased, which corresponded to a change in NO2/NO3 ratio in favor of NO3, the end product of NO transformations. The relation between mitochondrial protein nitrosylation with nitrosothiol formation and NO3release also changed towards the latter, which testified to the enhanced oxidation processes in the heart mitochondria after NG administration. Accordingly, a dose-dependent increase in lipid peroxidation products, an oxidative damage marker to the mitochondrial membranes, was demonstrated. It has been shown that the growth of ROS production (hydroxyl radical and mitochondrial H2O2 pool) is the basis of oxidative stress, as well as an increased content of free iron, derived from the oxidation of the mitochondrial iron-containing proteins. According to Fenton's reaction, interaction between iron and hydroperoxide, with NO3-derived hydroxyl radical and free radical peroxynitrite decomposition, is a possible cause of multifold increase in ROS production, as well as an increase in lipid peroxidation and oxidation of NO pools. MPTP blockade by nitric oxide, including that synthesized in the mitochondria in vivo, activated both constituents of NO-cycle, namely NO-synthase due to calcium-dependent activation of the mitochondrial NO-synthase, and nitrate reductase due to increased NO3pool. An increase in ROS production, magnified through the release of iron, results in mitochondrial oxidative stress and displacement of RNS metabolism towards the formation of NO3, the end product of nitric oxide transformations, despite nitrate reductase activation. It has been shown that MPTP opening in vitro also reduced ROS production, whereas its blockade by cyclosporin A restored ROS formation to the control values. The results obtained indicate that MPTP opening, preventing RNS and ROS overproduction both in vitro and in vivo, is an important component of the control of RNS and ROS metabolism in the mitochondria. PB Begell House LK https://www.dl.begellhouse.com/journals/6ec4ba27650016b1,464875f36b71f2d0,0291ce2737aa9883.html