Addition of insulin or a physiological ratio of ketone bodies to buffer with 10 mM glucose increased efficiency (hydraulic work/energy from O2 consumed) of working rat heart by 25%, and the two in combination increased efficiency by 36%. These additions increased the content of acetyl CoA by 9- to 18-fold, increased the contents of metabolites of the first third of the tricarboxylic acid (TCA) cycle 2- to 5-fold, and decreased succinate, oxaloacetate, and aspartate 2- to 3-fold. Succinyl CoA, fumarate, and malate were essentially unchanged. The changes in content of TCA metabolites resulted from a reduction of the free mitochondrial NAD couple by 2- to 10-fold and oxidation of the mitochondrial coenzyme Q couple by 2- to 4-fold. Cytosolic pH, measured using 31P-NMR spectra, was invariant at about 7.0. The total intracellular bicarbonate indicated an increase in mitochondrial pH from 7.1 with glucose to 7.2, 7.5 and 7.4 with insulin, ketones, and the combination, respectively. The decrease in Eh7 of the mitochondrial NAD couple, Eh7NAD+/NADH, from -280 to -300 mV and the increase in Eh7 of the coenzyme Q couple, Eh7Q/QH2, from -4 to +12 mV was equivalent to an increase from -53 kJ to -60 kJ/2 mol e in the reaction catalyzed by the mitochondrial NADH dehydrogenase multienzyme complex (EC 1.6.5.3). The increase in the redox energy of the mitochondrial cofactor couples paralleled the increase in the free energy of cytosolic ATP hydrolysis, delta GATP. The potential of the mitochondrial relative to the cytosolic phases, Emito/cyto, calculated from delta GATP and delta pH on the assumption of a 4 H+ transfer for each ATP synthesized, was -143 mV during perfusion with glucose or glucose plus insulin, and decreased to -120 mV on addition of ketones. Viewed in this light, the moderate ketosis characteristic of prolonged fasting or type II diabetes appears to be an elegant compensation for the defects in mitochondrial energy transduction associated with acute insulin deficiency or mitochondrial senescence.

Objectives In this study, we have investigated the effects of cannabidiol (CBD) on myocardial dysfunction, inflammation, oxidative/nitrosative stress, cell death and interrelated signaling pathways, using a mouse model of type I diabetic cardiomyopathy and primary human cardiomyocytes exposed to high glucose. Background CBD, the most abundant nonpsychoactive constituent of Cannabis sativa (marijuana) plant, exerts antiinflammatory effects in various disease models and alleviates pain and spasticity associated with multiple sclerosis in humans. Methods Left ventricular function was measured by pressure-volume system. Oxidative stress, cell death and fibrosis markers were evaluated by molecular biology/biochemical techniques, electron spin resonance spectroscopy and flow cytometry. Results Diabetic cardiomyopathy was characterized by declined diastolic and systolic myocardial performance associated with increased oxidative-nitrosative stress, NF-κB and MAPK (JNK and p-38, p38α) activation, enhanced expression of adhesion molecules (ICAM-1, VCAM-1), TNF-α, markers of fibrosis (TGF-β, CTGF, fibronectin, collagen-1, MMP-2 and MMP-9), enhanced cell death (caspase 3/7 and PARP activity, chromatin fragmentation and TUNEL) and diminished Akt phosphorylation. Remarkably, CBD attenuated myocardial dysfunction, cardiac fibrosis, oxidative/nitrosative stress, inflammation, cell death, and interrelated signaling pathways. Furthermore, CBD also attenuated the high glucose-induced increased reactive oxygen species generation, NF-κB activation and cell death in primary human cardiomyocytes. Conclusions Collectively, these results coupled with the excellent safety and tolerability profile of cannabidiol in humans, strongly suggest that it may have great therapeutic potential in the treatment of diabetic complications, and perhaps other cardiovascular disorders, by attenuating oxidative/nitrosative stress, inflammation, cell death and fibrosis.

The heroin analogue 1-methyl-4-phenylpyridinium, MPP + , both in vitro and in vivo , produces death of dopaminergic substantia nigral cells by inhibiting the mitochondrial NADH dehydrogenase multienzyme complex, producing a syndrome indistinguishable from Parkinson's disease. Similarly, a fragment of amyloid protein, Aβ 1–42 , is lethal to hippocampal cells, producing recent memory deficits characteristic of Alzheimer's disease. Here we show that addition of 4 mM d -β-hydroxybutyrate protected cultured mesencephalic neurons from MPP + toxicity and hippocampal neurons from Aβ 1–42 toxicity. Our previous work in heart showed that ketone bodies, normal metabolites, can correct defects in mitochondrial energy generation. The ability of ketone bodies to protect neurons in culture suggests that defects in mitochondrial energy generation contribute to the pathophysiology of both brain diseases. These findings further suggest that ketone bodies may play a therapeutic role in these most common forms of human neurodegeneration.

Mukhopadhyay P, Rajesh M, Bátkai S, Yoshihiro K, Haskó G, Liaudet L, Szabó C, Pacher P. Role of superoxide, nitric oxide, and peroxynitrite in doxorubicin-induced cell death in vivo and in vitro. Am J Physiol Heart Circ Physiol 296: H1466 -H1483, 2009. First published March 13, 2009 doi:10.1152/ajpheart.00795.2008.-Doxorubicin (DOX) is a potent available antitumor agent; however, its clinical use is limited because of its cardiotoxicity. Cell death is a key component in DOX-induced cardiotoxicity, but its mechanisms are elusive. Here, we explore the role of superoxide, nitric oxide (NO), and peroxynitrite in DOX-induced cell death using both in vivo and in vitro models of cardiotoxicity. Western blot analysis, real-time PCR, immunohistochemistry, flow cytometry, fluorescent microscopy, and biochemical assays were used to determine the markers of apoptosis/necrosis and sources of NO and superoxide and their production. Left ventricular function was measured by a pressure-volume system. We demonstrated increases in myocardial apoptosis (caspase-3 cleavage/activity, cytochrome c release, and TUNEL), inducible NO synthase (iNOS) expression, mitochondrial superoxide generation, 3-nitrotyrosine (NT) formation, matrix metalloproteinase (MMP)-2/MMP-9 gene expression, poly(ADP-ribose) polymerase activation [without major changes in NAD(P)H oxidase isoform 1, NAD(P)H oxidase isoform 2, p22phox , xanthine oxidase, endothelial NOS, and neuronal NOS expression] and decreases in myocardial contractility, catalase, and glutathione peroxidase activities 5 days after DOX treatment to mice. All these effects of DOX were markedly attenuated by peroxynitrite scavengers. Doxorubicin dose dependently increased mitochondrial superoxide and NT generation and apoptosis/necrosis in cardiac-derived H9c2 cells. DOX-or peroxynitrite-induced apoptosis/necrosis positively correlated with intracellular NT formation and could be abolished by peroxynitrite scavengers. DOX-induced cell death and NT formation were also attenuated by selective iNOS inhibitors or in iNOS knockout mice. Various NO donors when coadministered with DOX but not alone dramatically enhanced DOX-induced cell death with concomitant increased NT formation. DOX-induced cell death was also attenuated by cell-permeable SOD but not by cell-permeable catalase, the xanthine oxidase inhibitor allopurinol, or the NADPH oxidase inhibitors apocynine or diphenylene iodonium. Thus, peroxynitrite is a major trigger of DOX-induced cell death both in vivo and in vivo, and the modulation of the pathways leading to its generation or its effective neutralization can be of significant therapeutic benefit. heart failure; apoptosis; inducible nitric oxide synthase; hemodynamics BECAUSE OF ITS unmatched efficacy and broad-spectrum effect, doxorubicin (DOX; Adriamycin), an anthracycline antibiotic, continues to be a widely used chemotherapeutic agent to treat a variety of cancers (55) despite its potential to elicit serious dose-dependent cardiotoxicity often leading to degenerative cardiomyopathy...

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Alzheimer’s disease (AD) involves progressive accumulation of amyloid β-peptide (Aβ) and neurofibrillary pathologies, and glucose hypometabolism in brain regions critical for memory. The 3xTgAD mouse model was used to test the hypothesis that a ketone ester–based diet can ameliorate AD pathogenesis. Beginning at a presymptomatic age, 2 groups of male 3xTgAD mice were fed a diet containing a physiological enantiomeric precursor of ketone bodies (KET) or an isocaloric carbohydrate diet. The results of behavioral tests performed at 4 and 7 months after diet initiation revealed that KET-fed mice exhibited significantly less anxiety in 2 different tests. 3xTgAD mice on the KET diet also exhibited significant, albeit relatively subtle, improvements in performance on learning and memory tests. Immunohistochemical analyses revealed that KET-fed mice exhibited decreased Aβ deposition in the subiculum, CA1 and CA3 regions of the hippocampus, and the amygdala. KET-fed mice exhibited reduced levels of hyperphosphorylated tau deposition in the same regions of the hippocampus, amygdala, and cortex. Thus, a novel ketone ester can ameliorate proteopathic and behavioral deficits in a mouse AD model.

Sir2 is a NAD(+)-dependent histone deacetylase that controls gene silencing, cell cycle, DNA damage repair, and life span. Prompted by the observation that the [NAD(+)]/[NADH] ratio is subjected to dynamic fluctuations in skeletal muscle, we have tested whether Sir2 regulates muscle gene expression and differentiation. Sir2 forms a complex with the acetyltransferase PCAF and MyoD and, when overexpressed, retards muscle differentiation. Conversely, cells with decreased Sir2 differentiate prematurely. To inhibit myogenesis, Sir2 requires its NAD(+)-dependent deacetylase activity. The [NAD(+)]/[NADH] ratio decreases as muscle cells differentiate, while an increased [NAD(+)]/[NADH] ratio inhibits muscle gene expression. Cells with reduced Sir2 levels are less sensitive to the inhibition imposed by an elevated [NAD(+)]/[NADH] ratio. These results indicate that Sir2 regulates muscle gene expression and differentiation by possibly functioning as a redox sensor. In response to exercise, food intake, and starvation, Sir2 may sense modifications of the redox state and promptly modulate gene expression.

Experiments with isolated mitochondria have established that these organelles are pivotal intracellular sources of superoxide in a variety of pathophysiological conditions. Recently, a novel fluoroprobe MitoSOX Red was introduced for selective detection of superoxide in the mitochondria of live cells and was validated with confocal microscopy. Here we show ~3-7 fold dose-and timedependent increase in mitochondrial superoxide production (measured by MitoSOX using flow cytometry and confocal microscopy) in rat cardiac derived H9c2 myocytes and/or in human coronary artery endothelial cells triggered by Antimycin A, Paraquat, Doxorubicin or high glucose. These results establish a novel, quantitative method for simple detection of mitochondrial superoxide generation simultaneously in a large population of live cells by flow cytometry. This method can also be adapted for immune cell studies with mixed population of T or B cells or their subsets to analyze mitochondrial superoxide levels using multiple labeled surface markers in individual populations. KeywordsSuperoxide; Mitochondria; Free radicals; MitoSOX; Antimycin A (AntA); Paraquat (PQ); Doxorubicin (DOX); Cardiomyocytes; H9c2; Human coronary artery endothelial cells (HCAECs)The recognition that the free radical superoxide anion could be a biologically significant molecule has stimulated an extraordinary impetus for scientific research in all the fields of biology and medicine [1][2][3]. Under various pathological conditions several enzyme complexes, such as xanthine and NAD(P)H oxidases can be activated in many cellular systems to produce large amounts of superoxide [4,5]. There is increasing evidence (based mostly on experiments derived from isolated mitochondria) suggesting that mitochondrial dysfunction and interrelated intramitochondrial generation of superoxide anion and other reactive oxygen and nitrogen species (ROS and RNS) are also implicated in the pathophysiological processes associated with aging, cancer, neurodegenerative and inflammatory disorders, diabetes, and diabetic complications [6][7][8][9]. The recognition of the pivotal role of the mitochondria in the generation of ROS rekindled significant interest in the development of methods to assess the mitochondrial superoxide generation, which was largely hampered by the lack of a sensitive and specific assay [10][11][12]. Recently, a novel fluoroprobe MitoSOX Red (MitoSOX) was introduced for selective detection of superoxide in the mitochondria of live cells, and was validated with * Corresponding