We studied whether mitochondrial functions and Ca 2+ metabolism were altered in Wistar Kyoto normotensive (WKY) and spontaneous hypertensive rats (SHR). Ca 2+ uptake was decreased in SHR compared to WKY rats. Accumulation of Ca 2+ was more efficient in WKY than in SHR rats. mΔΨ was lower in SHR compared to WKY rats. Basal complex IV activity was higher in SHR than WKY rats, whereas basal L-citrulline production, an indicator of nitric oxide synthesis, was decreased in SHR and dependent on Ca 2+ concentration (p < 0.05). Impact of Ca 2+ was counteracted by EGTA. These data show an age-dependent decreased mitochondrial functions in brain mitochondria during hypertension.
Diabetes mellitus (DM) is a significant risk factor for the development of cardiovascular complications. This study was undertaken to investigate the effect of chronic administration of ethanolic extract of Eryngium carlinae on glucose, creatinine, uric acid, total cholesterol, and triglycerides levels in serum of streptozotocin- (STZ-) induced diabetic rats. Triglycerides, total cholesterol, and uric acid levels increased in serum from diabetic rats. The treatment with E. carlinae prevented these changes. The administration of E. carlinae extract reduced the levels of creatinine, uric acid, total cholesterol, and triglycerides. Thus administration of E. carlinae is able to reduce hyperlipidemia related to the cardiovascular risk in diabetes mellitus.
During the mezcal fermentation process, yeasts are affected by several stresses that can affect their fermentation capability. These stresses, such as thermal shock, ethanol, osmotic and growth inhibitors are common during fermentation. Cells have improved metabolic systems and they express stress response genes in order to decrease the damage caused during the stress, but to the best of our knowledge, there are no published works exploring the effect of oxidants and prooxidants, such as H2O2 and menadione, during growth. In this article, we describe the behavior of Kluyveromyces marxianus isolated from spontaneous mezcal fermentation during oxidative stress, and compared it with that of Saccharomyces cerevisiae strains that were also obtained from mezcal, using the W303-1A strain as a reference. S. cerevisiae strains showed greater viability after oxidative stress compared with K. marxianus strains. However, when the yeast strains were grown in the presence of oxidants in the media, K. marxianus exhibited a greater ability to grow in menadione than it did in H2O2. Moreover, when K. marxianus SLP1 was grown in a minibioreactor, its behavior when exposed to menadione was different from its behavior with H2O2. The yeast maintained the ability to consume dissolved oxygen during the 4 h subsequent to the addition of menadione, and then stopped respiration. When exposed to H2O2, the yeast stopped consuming oxygen for the following 8 h, but began to consume oxygen when stressors were no longer applied. In conclusion, yeast isolated from spontaneous mezcal fermentation was able to resist oxidative stress for a long period of time.
The deleterious effects of H 2 O 2 on the electron transport chain of yeast mitochondria and on mitochondrial lipid peroxidation were evaluated. Exposure to H 2 O 2 resulted in inhibition of the oxygen consumption in the uncoupled and phosphorylating states to 69% and 65%, respectively. The effect of H 2 O 2 on the respiratory rate was associated with an inhibition of succinateubiquinone and succinate-DCIP oxidoreductase activities. Inhibitory effect of H 2 O 2 on respiratory complexes was almost completely recovered by β-mercaptoethanol treatment. H 2 O 2 treatment resulted in full resistance to Q O site inhibitor myxothiazol and thus it is suggested that the quinol oxidase site (Q O ) of complex III is the target for H 2 O 2 . H 2 O 2 did not modify basal levels of lipid peroxidation in yeast mitochondria. However, H 2 O 2 addition to rat brain and liver mitochondria induced an increase in lipid peroxidation. These results are discussed in terms of the known physiological differences between mammalian and yeast mitochondria.
In isolated rat heart mitochondria, L-arginine is oxidized by a nitric oxide synthase (mtNOS) achieving maximal rates at 1 mM L-arginine. The NOS inhibitor N(G)-nitro-L-arginine methyl ester (NAME) inhibits the increase in NO production. Extramitochondrial free magnesium inhibited NOS production by 59% at 3.2 mM. The mitochondrial free Mg(2+) concentration increased to different extents in the presence of L-arginine (29%), the NO donor (S-nitroso-N-acetylpenicillamine) (105%) or the NOS inhibitors L-NAME (48%) or N(G)-nitro-L-arginine methyl ester, N(G)-monomethyl-L-arginine (L-NMMA) (53%). Under hypoxic conditions, mtNOS activity was inhibited by Mg(2+) by up to 50% after 30 min of incubation. Reoxygenation restored the activity of the mtNOS to pre-hypoxia levels. The results suggest that in heart mitochondria there is an interaction between Mg(2+) levels and mtNOS activity which in turn is modified by hypoxia and reoxygenation.
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