A new insight into the molecular hydrogen effect on coenzyme Q and mitochondrial function of rats.

Mitochondria are the major source of cellular energy metabolism. In the cardiac cells, mitochondria produce by way of the oxidative phosphorylation more than 90% of the energy supply in the form of ATP, which is utilized in many ATP-dependent processes, like cycling of the contractile proteins or maintaining ion gradients. Reactive oxygen species (ROS) are by-products of cellular metabolism and their levels are controlled by intracellular antioxidant systems. Imbalance between ROS and the antioxidant defense leads to oxidative stress and oxidative changes to cellular biomolecules. Molecular hydrogen (H2) has been proved as beneficial in the prevention and therapy of various diseases including cardiovascular disorders. It selectively scavenges hydroxyl radical and peroxynitrite, reduces oxidative stress, and has anti-inflammatory and anti-apoptotic effects. The effect of H2 on the myocardial mitochondrial function and coenzyme Q levels is not well known. In this paper, we demonstrated that consumption of H2-rich water (HRW) resulted in stimulated rat cardiac mitochondrial electron respiratory chain function and increased levels of ATP production by Complex I and Complex II substrates. Similarly, coenzyme Q9 levels in the rat plasma, myocardial tissue, and mitochondria were increased and malondialdehyde level in plasma was reduced after HRW administration. Based on obtained data, we hypothesize a new metabolic pathway of the H2 effect in mitochondria on the Q-cycle and in mitochondrial respiratory chain function. The Q-cycle contains three coenzyme Q forms: coenzyme Q in oxidized form (ubiquinone), radical form (semiquinone), or reduced form (ubiquinol). H2 may be a donor of both electron and proton in the Q-cycle and thus we can suppose stimulation of coenzyme Q production. When ubiquinone is reduced to ubiquinol, lipid peroxidation is reduced. Increased CoQ9 concentration can stimulate electron transport from Complex I and Complex II to Complex III and increase ATP production via mitochondrial oxidative phosphorylation. Our results indicate that H2 may function to prevent/treat disease states with disrupted myocardial mitochondrial function.

In vivo and in vitro assessment of brain bioenergetics in aging rats.

Brain energy disorders can be present in aged men and animals. To this respect, the mitochondrial and free radical theory of aging postulates that age-associated brain energy disorders are caused by an imbalance between pro- and anti-oxidants that can result in oxidative stress. Our study was designed to investigate brain energy metabolism and the activity of endogenous antioxidants during their lifespan in male Wistar rats. In vivo brain bioenergetics were measured using ³¹P nuclear magnetic resonance (NMR) spectroscopy and in vitro by polarographic analysis of mitochondrial oxidative phosphorylation. When compared to the young controls, a significant decrease of age-dependent mitochondrial respiration and adenosine-3-phosphate (ATP) production measured in vitro correlated with significant reduction of forward creatine kinase reaction (kfor) and with an increase in phosphocreatine (PCr)/ATP, PCr/Pi and PME/ATP ratio measured in vivo. The levels of enzymatic antioxidants catalase, GPx and GST significantly decreased in the brain tissue as well as in the peripheral blood of aged rats. We suppose that mitochondrial dysfunction and oxidative inactivation of endogenous enzymes may participate in age-related disorders of brain energy metabolism.

Mitochondrial function in heart and kidney of spontaneously hypertensive rats: influence of captopril treatment.

Effect of captopril treatment on capability of heart and kidney mitochondria to produce ATP was investigated in spontaneously hypertensive rats (SHR). Heart mitochondria from SHR responded to hypertension with tendency to compensate the elevated energy demands of cardiac cells by moderate increase in mitochondrial Mg2+-ATPase activity, membrane fluidity (MF) and in majority of functional parameters of the mitochondria (p>0.05). Significant increase exhibited only the oxygen consumption (QO2; p<0.01-0.001) and oxidative phosphorylation rate (OPR; p<0.003) with glutamate+malate (GLUT+MAL) as substrates. Lowering the blood pressure (p<0.02) captopril also eliminated the above compensatory response and impaired the oxidative ATP production by decreasing OPR (p<0.001). Kidney mitochondria of SHR experienced serious disarrangement in parameters of oxidative ATP production: increase in Mg2+-ATPase activity (p<0.05) but, also scattered QO2 values (p<0.03-0.01) leading to decrease in OPR and the ADP:O (p<0.05-0.01) values with both GLUT+MAL and succinate as substrates. Captopril treatment does not alleviated but even worsened the above alterations. Mg2+-ATPase became also decreased and the depression of ADP:O became aggravated (p<0.0001).

Influence of pyridoxylidene aminoguanidine on biomarkers of the oxidative stress and selected metabolic parameters of rats with diabetes mellitus.

Oxidative damage is considered to play an important role in the pathogenesis of several diseases, such as diabetes mellitus (DM), atherosclerosis, cardiovascular complications and chronic renal failure. DM is associated with the oxidative stress and formation of advanced glycation end products (AGEs). Different drugs inhibit oxidative stress and formation of advanced glycation end products. Aminoguanidine (AG) has been proposed as a drug of potential benefit in prophylaxis of the complications of DM. Recent reports show a pro-oxidant activity of AG. Therefore we examined the effect of structural analogue of AG, its Schiff base with pyridoxal-pyridoxylidene aminoguanidine (PAG) on the level of selected markers of oxidative stress. We found that PAG decreased total damage to DNA in controls as well as in diabetic group of rats. However, we also found that PAG supplementation increases susceptibility of lipoproteins to oxidation and formation of conjugated dienes in both, diabetic as well as control animals. Its administration to diabetic rats decreases antioxidant capacity of plasma. Therefore, it is necessary to search for other structural modifications of AG that would combine its higher anti-diabetic activity with less toxicity.

Study of the oxidative stress in a rat model of chronic brain hypoperfusion.

A multiple analysis of the cerebral oxidative stress was performed on a physiological model of dementia accomplished by three-vessel occlusion in aged rats. The forward rate constant of creatine kinase, k(for), was studied by saturation transfer (31)P magnetic resonance spectroscopy in adult and aged rat brain during chronic hypoperfusion. In addition, free radicals in aging rat brain homogenates before and/or after occlusion were investigated by spin-trapping electron paramagnetic resonance spectroscopy (EPR). Finally, biochemical measurements of oxidative phosphorylation parameters in the above physiological model were performed. The significant reduction of k(for) in rat brain compared to controls 2 and 10 weeks after occlusion indicates a disorder in brain energy metabolism. This result is consistent with the decrease of the coefficient of oxidative phosphorylation (ADP:O), and the oxidative phosphorylation rate measured in vitro on brain mitochondria. The EPR study showed a significant increase of the ascorbyl free radical concentration in this animal model. Application of alpha-phenyl-N-tert-butylnitrone (PBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin traps revealed formation of highly reactive hydroxyl radical (.OH) trapped in DMSO as the .CH(3) adduct. It was concluded that the ascorbate as a major antioxidant in brain seems to be useful in monitoring chronic cerebral hypoperfusion.

Effects of coenzyme Q and creatine supplementation on brain energy metabolism in rats exposed to chronic cerebral hypoperfusion.

It is known that oxidative stress and mitochondrial dysfunction both play an important role in animal models of brain ischemia. The present study was undertaken to test whether oral supplementation of coenzyme Q10 (ubiquinone) or creatine citrate could protect against brain ischemia-induced mitochondrial damage in the rats model. Brain ischemia was induced for 50 minutes with three-vessel occlusion (3-VO). Coenzyme Q10 was administered for 30 days before the ischemic event and coenzyme Q10 or creatine citrate for 30 days post-ischemia. Moreover, the concentrations of coenzyme Q10 and α-, γ- tocopherols as well as the formation of thiobarbituric acid reactive substances (TBARS) were measured in brain mitochondria and in plasma. Transient hypoperfusion revealed significant impairment in brain energy metabolism as detected by mitochondrial oxidative phosphorylation as well as decreased concentrations of brain and plasma endogenous antioxidants and increased formation of TBARS in plasma. When compared with the ischemic group, supplementation of coenzyme Q10 was ineffective as a preventive agent. However, the positive effect of therapeutic coenzyme Q10 supplementation was supported by the oxygen consumption values (p < 0.05) and ATP production (p < 0.05) in brain mitochondria, as well as by increased concentration of coenzyme Q9 (p < 0.05) and concentration of α-tocopherol (p < 0.05) in brain mitochondria and by increased concentration of α-tocopherol (p < 0.05) and γ-tocopherol in plasma. This suggests that coenzyme Q10 therapy involves resistance to oxidative stress and improved brain bioenergetics, when supplemented during reperfusion after ischemic brain injury.