Triiodothyronine administration before partial hepatectomy increased the activity of mitochondrial glycerophosphate cytochrome c reductase. The enzyme activity was further activated after partial hepatectomy during the regenerative process. Our findings showed that: a) the increase of glycerophosphate cytochrome c reductase induced by triiodothyronine was further potentiated by the regeneration process, b) the high activity of the glycerophosphate shuttle was maintained after partial hepatectomy during the period, when most of the liver tissue had again been recovered., H. Lotková, H. Rauchová, Z. Drahota., and Obsahuje bibliografii
Digitonin solubilizes mitochondrial membrane, breaks the integrity of the respiratory chain and releases two mobile redoxactive components: coenzyme Q (CoQ) and cytochrome c (cyt c). In the present study we report the inhibition of glycerol-3- phosphate- and succinate-dependent oxygen consumption rates by digitonin treatment. Our results show that the inhibition of oxygen consumption rates is recovered by the addition of exogenous synthetic analog of CoQ idebenone (hydroxydecylubiquinone; IDB) and cyt c. Glycerol-3-phosphate oxidation rate is recovered to 148 % of control values, whereas succinatedependent oxidation rate only to 68 %. We find a similar effect on the activities of glycerol-3-phosphate and succinate cytochrome c oxidoreductase. Our results also indicate that succinate-dependent oxidation is less sensitive to digitonin treatment and less activated by IDB in comparison with glycerol- 3-phosphate-dependent oxidation. These findings might indicate the different mechanism of the electron transfer from two flavoprotein-dependent dehydrogenases (glycerol-3-phosphate dehydrogenase and succinate dehydrogenase) localized on the outer and inner face of the inner mitochondrial membrane, respectively., H. Rauchová, M. Vokurková, Z. Drahota., and Obsahuje seznam literatury
Mitochondria as an energy generating cell device are very sensitive to oxidative damage. Our previous findings obtained in hepatocytes demonstrated that Complex I of the respiratory chain is more sensitive to oxidative damage than other respiratory chain complexes. We present additional data on isolated mitochondria showing that palmityl carnitine oxidation is strongly depressed at a low (200 μM) tert-butyl hydroperoxide (tBHP) concentration, while oxidation of the flavoprotein-dependent substrate - succinate is not affected and neither is ATP synthesis inhibited by tBHP. In the presence of tBHP, the respiratory control index for palmityl carnitine oxidation is strongly depressed, but when succinate is oxidized the respiratory control index remains unaffected. Our findings thus indicate that flavoprotein-dependent substrates could be an important nutritional factor for the regeneration process in the necrotic liver damaged by oxidative stress., Z. Červinková, H. Rauchová, P. Křiváková, Z. Drahota., and Obsahuje bibliografii a bibliografické odkazy
The concentration-dependence of tert-butyl hydroperoxide (BHP) inhibitory effect on oxygen consumption in isolated rat liver mitochondria was measured in the presence of various respiratory substrates. Strong inhibitory effect at low concentrations of BHP (15-30 μM) was found for oxoglutarate and palmitoyl carnitine oxidation. Pyruvate and glutamate oxidation was inhibited at higher concentrations of BHP (100-200 μM). Succinate oxidation was not affected even at 3.3 mM BHP. Determination of mitochondrial membrane potential has shown that in the presence of NADH-dependent substrates the membrane potential was dissipated by BHP but was completely restored after addition of succinate. Our data thus indicate that beside peroxidative damage of complex I also various mitochondrial NADH-dependent dehydrogenases are inhibited, but to a different extent and with different kinetics. Our data also show that succinate could be an important nutritional substrate protecting hepatocytes during peroxidative damage., R. Endlicher ... [et al.]., and Obsahuje seznam literatury
The activities of cytochrome c oxidase and FoF1-ATPase as well as the content of cytochromes cc1, aa3, and b were investigated in free brain mitochondria in the course of postnatal development and aging. The results show an increase of Vmax of both enzymes during postnatal development (between day 5 and 30). During the following phase ending at the age of 6 months, a decrease of FoF1-ATPase and cytochrome c oxidase activity occurs. From 6 to 12 months of age the activity of these enzymes did not change. The KM for both enzymes remained unchanged during the whole period observed. The content of cytochromes increased from the low values found in young rats, reached the highest values at around one month, and decreased till the age of 3 months. Later, their content in brain mitochondria did not markedly change. Our results suggest that the metabolic maturation of brain mitochondria differs in several aspects from the same process in other tissues, mainly in the time course. This is probably due to the unique role of neural tissue in the organism., M. Kalous, H. Rauchová, Z. Drahota., and Obsahuje bibliografii
Lipid peroxidation of rat cerebral cortex membranes was induced by Fe2+/ADP and ascorbate. The rate of Na+/K+-ATPase inhibition was correlated with the increase of thiobarbituric acid-reactive substances (TBARS) and conjugated dienes (CD) and with membrane fluidity changes. Our data showed that membrane fluidity changes (evaluated by fluorescence steady-state anisotropy measurements) can participate in Na+/K+-ATPase inhibition during the initial period of lipid peroxidation process, whereas during the following period the enzyme inhibition correlates only with TBARS and CD production., H. Rauchová, Z. Drahota, J. Koudelová., and Obsahuje bibliografii