Akopova O V, Korkach Iu P, Kotsiuruba A V, Kolchyns'ka L I, Sagach V F
Fiziol Zh (1994). 2012;58(2):3-15.
Some aspects of reactive nitrogen and oxygen species (RNS and ROS) metabolism in rat heart mitochondria under administration of different doses of nitroglycerine (NG) in vivo are discussed. It is shown that NG administration results in a dose-dependent increase in Ca2+-uptake in mitochondria, due to the dose-dependent inhibition of mitochondrial permeability transition pore (MPTP) in vivo and the activation of Ca2+-dependent mitochondrial NOS. It was shown that NOS activity increases in accord with the increase of Ca2+-uptake in mitochondria. The dose-dependent activation of nitratreductase is observed. However, nitrite production decreases dose-dependently, according to the change of NO2-/NO3- ratio on behalf of NO3-, the end product of NO transformations. The relation between nitrosylation of mitochondrial proteins with the nitrosothiols formation and nitrate production also changes towards NO3-, which shows the activation of oxidation reactions in heart mitochondria after NG administration. Accordingly, dose-dependent increase in lipid peroxidation (LP) products is shown, the hallmark of the membrane damage in mitochondria. It is established that the cause of oxidative stress, besides the dose-dependent increase in ROS production (hydroperoxide, superoxide and hydroxyl-radical), lies in the increase of free iron content, derived from the oxidation of mitochondrial iron-containing proteins. The iron interaction with hydroperoxide following Fenton reaction as well as free-radical decomposition ofperoxynitrite, derived from NO3- are the possible cause of manifold increase in ROS as well as LP production, and RNS oxidation to NO3-. Thus, NO-dependent MPTP blockage, due to NO synthesis in mitochondria in vivo, results in the activation of both constituents of NO-cycle: NOS-dependent, due to Ca2+-dependent activation of mitochondrial NOS, and nitrate-reductase-dependent, due to the increase in NO3- formation. However, increase in ROS production, augmented by the iron release, leads to the oxidative stress and the shift of RNS metabolism towards NO3- formation, in spite of the activation of nitrate-reductase-dependent pathway of NO-cycle. It is shown that reversible MPTP opening in vitro diminishes ROS production, whereas MPTP blockage by cyclosporine A restores the ROS formation to control level. Thus, MPTP-dependent inhibition of ROS overproduction both in vitro and in vivo, shows the importance of MPTP in the regulation of ROS and RNS metabolism in mitochondria.
本文讨论了在体内给予不同剂量硝酸甘油（NG）后，大鼠心脏线粒体中活性氮和氧物种（RNS和ROS）代谢的某些方面。结果表明，由于体内线粒体通透性转换孔（MPTP）的剂量依赖性抑制和Ca2+依赖性线粒体一氧化氮合酶（NOS）的激活，NG给药导致线粒体Ca2+摄取量呈剂量依赖性增加。研究表明，NOS活性随着线粒体Ca2+摄取量的增加而增加。观察到硝酸还原酶的剂量依赖性激活。然而，随着NO转化终产物NO3-导致的NO2-/NO3-比值变化，亚硝酸盐生成量呈剂量依赖性减少。线粒体蛋白亚硝化与亚硝基硫醇形成和硝酸盐生成之间的关系也向NO3-方向变化，这表明NG给药后心脏线粒体中氧化反应的激活。相应地，脂质过氧化（LP）产物呈剂量依赖性增加，这是线粒体膜损伤的标志。已确定，除了ROS生成（氢过氧化物、超氧化物和羟基自由基）的剂量依赖性增加外，氧化应激的原因还在于线粒体含铁蛋白氧化产生的游离铁含量增加。铁与氢过氧化物按照芬顿反应相互作用以及由NO3-衍生的过氧亚硝酸盐的自由基分解，可能是ROS以及LP生成量大幅增加以及RNS氧化为NO3-的原因。因此，由于体内线粒体中NO的合成，NO依赖性MPTP阻断导致NO循环的两个组成部分被激活：由于线粒体NOS的Ca2+依赖性激活而依赖于NOS，以及由于NO3-形成增加而依赖于硝酸还原酶。然而，尽管NO循环的硝酸还原酶依赖性途径被激活，但铁释放导致的ROS生成增加导致氧化应激以及RNS代谢向NO3-形成的转变。结果表明，体外可逆性MPTP开放可减少ROS生成，而环孢素A对MPTP的阻断可将ROS生成恢复到对照水平。因此，MPTP在体外和体内对ROS过量生成的依赖性抑制表明了MPTP在线粒体ROS和RNS代谢调节中的重要性。
