Coenzyme Qio (CoQio) levels in human plasma were determined by high-performance liquid chromatography (HPLC) with UV detection. CoQio was dissociated from lipoproteins by methanol and subsequently cleaned-up on silica gel and octadecyl silica solid-phase extraction cartridges. HPLC separation was performed on a Cis reversed-phase column. The methanol-hexane mobile phase provided a greater possibility of separation procedure adjustment allowing the shortest possible elution time without loss of resolution than a two-alcohol mobile phase. Quantitation was based on the peak heights using a standard addition method. The lower limit of detection was 8 ng on-column, corresponding to 90 //g ubiquinone per litre of plasma in an actual sample. Thirty-one randomly selected plasma samples from apparently healthy, 18 to 56-year-old individuals (males and females) were analyzed for total CoQio. The average level in these subjects was 0.47±0.18 mg/1 with the range of 0.26-1.03 mg/1. The method was also applied to the determination of ubiquinone plasma level changes in one healthy volunteer over a period of one month and after oral intake of CoQio.
Dysfunction of mitochondria induced by ischemia is considered to be a key event triggering neuronal cell death after brain ischemia. Here we report the effect of ischemia-reperfusion on mitochondrial protein synthesis and activity of cytochrome c oxidase (EC 1.9.3.1, COX). By performing 4-vessel occlusion model of global brain ischemia, we have observed that 15 min of global ischemia led to the inhibition of COX subunit I (COXI) synthesis to 56 % of control. After 1, 3 and 24 h of reperfusion, COXI synthesis was inhibited to 46, 50 and 72 % of control, respectively. Depressed synthesis of COXI was not a result of either diminished transcription of COXI gene or increased proteolytic degradation of COXI, since both Northern hybridization and Western blotting did not show significant changes in COXI mRNA and protein level. Thus, ischemia-reperfusion affects directly mitochondrial translation machinery. In addition, ischemia in duration of 15 min and consequent 1, 3 and 24 h of reperfusion led to the inhibition of COX activity to 90.3, 80.3, 81.9 and 83.5 % of control, respectively. Based on our data, we suggest that inhibition of COX activity is rather caused by ischemia-induced modification of COX polypeptides than by inhibition of mitochondrial translation., P. Racay ... [et al.]., and Obsahuje seznam literatury