Nuanxin capsule enhances cardiac function by inhibiting oxidative stress-induced mitochondrial dependent apoptosis through AMPK/JNK signaling pathway.

OBJECTIVE: Oxidative stress and apoptosis play critical roles in the pathogenesis of heart failure (HF).Nuanxin capsule (NX) is a Chinese medicine that has outstanding protective effects on HF. The present study aimed to elucidate whether NX could protect HF against oxidative stress-induced apoptosis through intrinsic mitochondrial pathway. METHODS: In vivo, HF was induced by transverse aortic constriction. NX and Compound C (Comp C) were administered to C57BL/6 J mice for over a 4-week period. Cardiac function was assessed with echocardiography. In vitro, H9c2 cells were exposed to H2O2 in the presence or absence of NX and Compound C. Cell viability, cytotoxicity, reactive oxygen species (ROS) production, apoptosis, mitochondrial membrane potential (ΔΨm) and mitochondrial function by oxygen consumption rate (OCR) were detected. The expressions of cytochrome c, BAX, Bcl-2, cleaved caspase-3, AMPK and JNK were evaluated by western blotting. RESULTS: The results indicated that NX significantly improved cardiac function and enhanced the cell viability, ΔΨm and mitochondrial respiration. Also NX treatment reduced cell cytotoxicity and ROS production. Moreover, NX inhibited mitochondrial-mediated apoptosis by upregulating AMPK and downregulating JNK both in vivo and in vitro. The protective effects of NX on cardiac function by reducing oxidative stress-induced mitochondrial dependent apoptosis were reversed by Compound C treatment. CONCLUSIONS: These findings demonstrated that NX effectively improved cardiac function in TAC mice by reducing oxidative stress-induced mitochondrial dependent apoptosis by activating AMPK/JNK signaling pathway.

Bioenergetic consequences from xenotopic expression of a tunicate AOX in mouse mitochondria: Switch from RET and ROS to FET.

Electron transfer from all respiratory chain dehydrogenases of the electron transport chain (ETC) converges at the level of the quinone (Q) pool. The Q redox state is thus a function of electron input (reduction) and output (oxidation) and closely reflects the mitochondrial respiratory state. Disruption of electron flux at the level of the cytochrome bc1 complex (cIII) or cytochrome c oxidase (cIV) shifts the Q redox poise to a more reduced state which is generally sensed as respiratory stress. To cope with respiratory stress, many species, but not insects and vertebrates, express alternative oxidase (AOX) which acts as an electron sink for reduced Q and by-passes cIII and cIV. Here, we used Ciona intestinalis AOX xenotopically expressed in mouse mitochondria to study how respiratory states impact the Q poise and how AOX may be used to restore respiration. Particularly interesting is our finding that electron input through succinate dehydrogenase (cII), but not NADH:ubiquinone oxidoreductase (cI), reduces the Q pool almost entirely (>90%) irrespective of the respiratory state. AOX enhances the forward electron transport (FET) from cII thereby decreasing reverse electron transport (RET) and ROS specifically when non-phosphorylating. AOX is not engaged with cI substrates, however, unless a respiratory inhibitor is added. This sheds new light on Q poise signaling, the biological role of cII which enigmatically is the only ETC complex absent from respiratory supercomplexes but yet participates in the tricarboxylic acid (TCA) cycle. Finally, we delineate potential risks and benefits arising from therapeutic AOX transfer.

Late-life Cardiac Injury in Rats following Early Life Exposure to Lead: Reversal Effect of Nutrient Metal Mixture.

Early-life exposure to lead (Pb) can lead to health effects in later life. The neurotoxic effects of Pb have been well documented but its effects on the heart are poorly elucidated. We examined the late life cardiac impairments resulting from developmental exposure to Pb. Further, we investigated the protective effect of the nutrient metal mixture containing calcium (Ca), zinc (Zn) and iron (Fe) against Pb-induced long-term effects on cardiac functions.Male albino rats were lactationally exposed to 0.2% Pb-acetate or 0.2% Pb-acetate together nutrient metal mixture as 0.02% in drinking water of the mother from PND 1 to PND 21. The results showed increased levels of serum total cholesterol (TC), triglycerides (TG), low-density lipoproteins (LDLs) and lactate dehydrogenase (LDH) activity at postnatal day (PND) 28 [young], 4 months [adult] and 18 months [old] age group rats. Most notably, exposure to Pb decreased the activities of mitochondrial superoxide dismutase (SOD), thioredoxin reductase (TrxR), aconitase (Acon), isocitrate dehydrogenase (ICDH), xanthine oxidase (XO) and total antioxidant status while the MDA levels increased in all selected age groups of rats. The histological findings showed an age-dependent response to Pb exposure evidenced by extensive degeneration and necrosis in cardiac muscle, disruption in muscle connectivity, hemorrhage, and mononuclear cell infiltration. Co-administration of nutrient metal mixture reversed the Pb-induced cardiac impairments as reflected in the recovery of the chosen sensitive markers of oxidative stress, reduced Pb levels and cardiac tissue changes. In conclusion, the data demonstrate that early-life exposure to Pb continuously influence the cardiac mitochondrial functions from early life to older age and further suggesting that adequate intake of nutrient metals may be potential therapeutic treatment for Pb intoxication.

Monomeric structure of an active form of bovine cytochrome c oxidase.

Cytochrome c oxidase (CcO), a membrane enzyme in the respiratory chain, catalyzes oxygen reduction by coupling electron and proton transfer through the enzyme with a proton pump across the membrane. In all crystals reported to date, bovine CcO exists as a dimer with the same intermonomer contacts, whereas CcOs and related enzymes from prokaryotes exist as monomers. Recent structural analyses of the mitochondrial respiratory supercomplex revealed that CcO monomer associates with complex I and complex III, indicating that the monomeric state is functionally important. In this study, we prepared monomeric and dimeric bovine CcO, stabilized using amphipol, and showed that the monomer had high activity. In addition, using a newly synthesized detergent, we determined the oxidized and reduced structures of monomer with resolutions of 1.85 and 1.95 Å, respectively. Structural comparison of the monomer and dimer revealed that a hydrogen bond network of water molecules is formed at the entry surface of the proton transfer pathway, termed the K-pathway, in monomeric CcO, whereas this network is altered in dimeric CcO. Based on these results, we propose that the monomer is the activated form, whereas the dimer can be regarded as a physiological standby form in the mitochondrial membrane. We also determined phospholipid structures based on electron density together with the anomalous scattering effect of phosphorus atoms. Two cardiolipins are found at the interface region of the supercomplex. We discuss formation of the monomeric CcO, dimeric CcO, and supercomplex, as well as their role in regulation of CcO activity.

Carnitine Supplementation Attenuates Sunitinib-Induced Inhibition of AMP-Activated Protein Kinase Downstream Signals in Cardiac Tissues.

This study has been initiated to investigate whether sunitinib (SUN) alters the expression of key genes engaged in mitochondrial transport and oxidation of long chain fatty acids (LCFA), and if so, whether these alterations should be viewed as a mechanism of SUN-induced cardiotoxicity, and to explore the molecular mechanisms whereby carnitine supplementation could attenuate SUN-induced cardiotoxicity. Adult male Wister albino rats were assigned to one of the four treatment groups: Rats in group 1 received no treatment but free access to tap water for 28 days. Rats in group 2 received L-carnitine (200 mg/kg/day) in drinking water for 28 days. Rats in group 3 received SUN (25 mg/kg/day) in drinking water for 28 days. Rats in group 4 received the same doses of L-carnitine and SUN in drinking water for 28 days. Treatment with SUN significantly increased heart weight, cardiac index, and cardiotoxicity enzymatic indices, as well as severe histopathological changes. Moreover, SUN significantly decreased level of adenosine monophosphate-activated protein kinase (AMPKα2), total carnitine, adenosine triphosphate (ATP) and carnitine palmitoyltransferase I (CPT I) expression and significantly increased acetyl-CoA carboxylase-2 (ACC2) expression and malonyl-CoA level in cardiac tissues. Interestingly, carnitine supplementation resulted in a complete reversal of all the biochemical, gene expression and histopathological changes-induced by SUN to the control values. In conclusion, data from this study suggest that SUN inhibits AMPK downstream signaling with the consequent inhibition of mitochondrial transport of LCFA and energy production in cardiac tissues. Carnitine supplementation attenuates SUN-induced cardiotoxicity.

Metabolic Maturation of Human Pluripotent Stem Cell-Derived Cardiomyocytes by Inhibition of HIF1α and LDHA.

RATIONALE: Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are a readily available, robustly reproducible, and physiologically appropriate human cell source for cardiac disease modeling, drug discovery, and toxicity screenings in vitro. However, unlike adult myocardial cells in vivo, hPSC-CMs cultured in vitro maintain an immature metabolic phenotype, where majority of ATP is produced through aerobic glycolysis instead of oxidative phosphorylation in the mitochondria. Little is known about the underlying signaling pathways controlling hPSC-CMs' metabolic and functional maturation. OBJECTIVE: To define the molecular pathways controlling cardiomyocytes' metabolic pathway selections and improve cardiomyocyte metabolic and functional maturation. METHODS AND RESULTS: We cultured hPSC-CMs in different media compositions including glucose-containing media, glucose-containing media supplemented with fatty acids, and glucose-free media with fatty acids as the primary carbon source. We found that cardiomyocytes cultured in the presence of glucose used primarily aerobic glycolysis and aberrantly upregulated HIF1α (hypoxia-inducible factor 1α) and its downstream target lactate dehydrogenase A. Conversely, glucose deprivation promoted oxidative phosphorylation and repressed HIF1α. Small molecule inhibition of HIF1α or lactate dehydrogenase A resulted in a switch from aerobic glycolysis to oxidative phosphorylation. Likewise, siRNA inhibition of HIF1α stimulated oxidative phosphorylation while inhibiting aerobic glycolysis. This metabolic shift was accompanied by an increase in mitochondrial content and cellular ATP levels. Furthermore, functional gene expressions, sarcomere length, and contractility were improved by HIF1α/lactate dehydrogenase A inhibition. CONCLUSIONS: We show that under standard culture conditions, the HIF1α-lactate dehydrogenase A axis is aberrantly upregulated in hPSC-CMs, preventing their metabolic maturation. Chemical or siRNA inhibition of this pathway results in an appropriate metabolic shift from aerobic glycolysis to oxidative phosphorylation. This in turn improves metabolic and functional maturation of hPSC-CMs. These findings provide key insight into molecular control of hPSC-CMs' metabolism and may be used to generate more physiologically mature cardiomyocytes for drug screening, disease modeling, and therapeutic purposes.

The Involvement of Cytochrome c Oxidase in Mitochondrial Fusion in Primary Cultures of Neonatal Rat Cardiomyocytes.

Cytochrome c oxidase (CCO) is a copper-dependent enzyme of mitochondrial respiratory chain. In pressure overload-induced cardiac hypertrophy, copper level and CCO activity are both depressed, along with disturbance in mitochondrial fusion and fission dynamics. Copper repletion leads to recovery of CCO activity and normalized mitochondrial dynamics. The present study was undertaken to define the link between CCO activity and mitochondrial dynamic changes. Primary cultures of neonatal rat cardiomyocytes were treated with phenylephrine to induce cell hypertrophy. Hypertrophic cardiomyocytes were then treated with copper to reverse hypertrophy. In the hypertrophic cardiomyocytes, CCO activity was depressed and mitochondrial fusion was suppressed. Upon copper repletion, CCO activity was recovered and mitochondrial fusion was reestablished. Depression of CCO activity by siRNA targeting CCO assembly homolog 17 (COX17), a copper chaperone for CCO, led to fragmentation of mitochondria, which was not recoverable by copper supplementation. This study thus demonstrates that copper-dependent CCO is critical for mitochondrial fusion in the regression of cardiomyocyte hypertrophy.

Garlic activates SIRT-3 to prevent cardiac oxidative stress and mitochondrial dysfunction in diabetes.

BACKGROUND: Cardiac complications are major contributor in the mortality of diabetic people. Mitochondrial dysfunctioning is a crucial contributor for the cardiac complications in diabetes, and SIRT-3 remains the major mitochondrial deacetylase. We hypothesized whether garlic has any role on SIRT-3 to prevent mitochondrial dysfunction in diabetic heart. METHODS: Rats with developed hyperglycemia after STZ injection were divided into two groups; diabetic (Dia) and diabetic+garlic (Dia+Garl). Garlic was administered at a dose of 250mg/kg/day, orally for four weeks. An additional group was maintained to evaluate the effect of raw garlic administration on control rat heart. RESULT: We have observed altered functioning of cardiac mitochondrial enzymes involved in metabolic pathways, and increased levels of cardiac ROS with decreased activity of catalase and SOD in diabetic rats. Cardiac mRNA expression of TFAM, PGC-1α, and CO1 was also altered in diabetes. In addition, reduced levels of electron transport chain complexes that observed in Dia group were normalized with garlic administration. This indicates the presence of increased oxidative stress with mitochondrial dysfunctioning in diabetic heart. We have observed reduced activity of SIRT3 and increased acetylation of MnSOD. Silencing SIRT-3 in cells also revealed the same. However, administration of garlic improved the SIRT-3 and MnSOD activity, by deacetylating MnSOD. Increased SOD activity was correlated with reduced levels of ROS in garlic-administered rat hearts. CONCLUSION: Collectively, our results provide an insight into garlic's protection to T1DM heart through activation of SIRT3-MnSOD pathway.

Conjugated linoleic acid and nitrite attenuate mitochondrial dysfunction during myocardial ischemia.

Cardiovascular health is influenced by dietary composition and the western diet is composed of varying types/amounts of fat. Conjugated linoleic acid (cLA) is an abundant dietary unsaturated fatty acid associated with health benefits but its biological signaling is not well understood. Nitrite is enriched in vegetables within the diet and can impact signaling of unsaturated fatty acids; however, its role on cLA signaling is not well understood. Elucidating how nitrite may impact the biological signaling of cLA is important due to the dietary consumption of both cLA and nitrite in the western diet. Since co-administration of cLA and nitrite results in cardioprotection during myocardial infarction (MI), it was hypothesized that cLA and nitrite may affect cardiac mitochondrial respiratory function and complex activity in MI. C57BL/6J mice were treated with cLA and nitrite for either 10 or 13days, where MI was induced on day 3. Following treatment, respiration and complex activity were measured. Among the major findings of this study, cLA treatment (10days) decreases state 3 respiration in vivo. Following MI, nitrite alone and in combination with cLA attenuates increased state 3 respiration and decreases hydrogen peroxide levels. Further, nitrite and cLA co-treatment attenuates increased complex III activity after MI. These results suggest that cLA, nitrite and the combination significantly alter cardiac mitochondrial respiratory and electron transport chain activity in vivo and following MI. Overall, the daily consumption of cLA and nitrite in the diet can have diverse cardiovascular implications, some of which occur at the mitochondrial level.

Coenzyme Q10 and Heart Failure: A State-of-the-Art Review.

Heart failure (HF) with either preserved or reduced ejection fraction is associated with increased morbidity and mortality. Evidence-based therapies are often limited by tolerability, hypotension, electrolyte disturbances, and renal dysfunction. Coenzyme Q10 (CoQ10) may represent a safe therapeutic option for patients with HF. CoQ10 is a highly lipophilic molecule with a chemical structure similar to vitamin K. Although being a common component of cellular membranes, CoQ10's most prominent role is to facilitate the production of adenosine triphosphate in the mitochondria by participating in redox reactions within the electron transport chain. Numerous trials during the past 30 years examining CoQ10 in patients with HF have been limited by small numbers and lack of contemporary HF therapies. The recent publication of the Q-SYMBIO randomized controlled trial demonstrated a reduction in major adverse cardiovascular events with CoQ10 supplementation in a contemporary HF population. Although having limitations, this study has renewed interest in evaluating CoQ10 supplementation in patients with HF. Current literature suggests that CoQ10 is relatively safe with few drug interactions and side effects. Furthermore, it is already widely available as an over-the-counter supplement. These findings warrant future adequately powered randomized controlled trials of CoQ10 supplementation in patients with HF. This state-of-the-art review summarizes the literature about the mechanisms, clinical data, and safety profile of CoQ10 supplementation in patients with HF.

Cardioprotection against ischemia/reperfusion injury by QiShenYiQi Pill® via ameliorate of multiple mitochondrial dysfunctions.

AIM: To investigate the potential cardioprotective effects of QiShenYiQi Pill(®) (QSYQ) on myocardial ischemia/reperfusion (I/R) injury through antioxidative stress and mitochondrial protection. METHODS AND RESULTS: Sprague Dawley rats were pretreated with QSYQ or saline for 7 days and subjected to ischemia (30 minutes occlusion of the left anterior descending coronary artery) and reperfusion (120 minutes). Cardiac functions were evaluated by echocardiogram and hemodynamics. Myocardial mitochondria were obtained to evaluate changes in mitochondrial structure and function, immediately after 120 minutes reperfusion. Pretreatment with QSYQ protected against I/R-induced myocardial structural injury and improved cardiac hemodynamics, as demonstrated by normalized serum creatine kinase and suppressed oxidative stress. Moreover, the impaired myocardial mitochondrial structure and function decreased level of ATP (accompanied by reduction of ATP5D and increase in the expression of cytochrome C). Myocardial fiber rupture, interstitial edema, and infiltrated leukocytes were all significantly ameliorated by pretreatment with QSYQ. CONCLUSION: Pretreatment of QSYQ in Sprague Dawley rats improves ventricular function and energy metabolism and reduces oxidative stress via ameliorating multiple mitochondrial dysfunctions during I/R injury.

Effects of acetaldehyde and L-carnitine on morphology and enzyme activity of myocardial mitochondria in rats.

This study aimed to investigate the effects of acetaldehyde (AA) and L-carnitine (LC) on morphology and enzyme activity of myocardial mitochondria in rats. Sixty-five Wistar rats were randomly divided into 4 groups: the control group (n = 20), the AA low-dose group (n = 15), the AA high-dose group (n = 15) and the AA + LC group (n = 15). Different doses (110 mg/kg and 220 mg/kg) AA was injected intraperitoneally once a day for 4 weeks. After 4 weeks administration, transmission electron microscope (TEM) observation of morphology of rat myocardial mitochondria was performed. Serum levels of succinate dehydrogenase (SDH), superoxide dismutase (SOD), malondialdehyde (MDA) and cardiac troponin I (cTnI) were detected to evaluate mitochondrial enzymes activities. Light micrograph of rat myocardiocytes in the control group showing normal architecture of myocytes. The numerical density and number of mitochondria in both low-dose and high-dose AA groups were lower than that of the control group. After administration of LC, the rats in the AA + LC group showed an obvious increase in the numerical density and number of mitochondria. TEM showed that both low-dose and high-dose AA could induce myocardial mitochondrial damage in rats in a dose-dependent manner, such as mitochondrial swelling, disruptions of crest and membrane, mitochondrial deficiency. The degree of mitochondrial damage of the AA + LC group was significantly decreased after administration of LC. Our results showed that serum levels of SDH and SOD in the AA + LC and control groups were also higher than those of the low-dose and high-dose AA groups; while the MDA level in the AA + LC and control groups were lower than that of the low-dose and high-dose AA groups. The low-dose AA, high-dose AA and AA + LC groups exhibited a higher level of serum cTnI than that of the control group. However, there was no significant difference in serum cTnI level among the low-dose AA, high-dose AA and AA + LC groups. Our findings indicate that AA may lead to myocardial mitochondrial damage and the induction of enzyme activity in rats, while administration of LC could alleviate AA-related damage of rat myocardial mitochondria.

Apolipoprotein A1 regulates coenzyme Q10 absorption, mitochondrial function, and infarct size in a mouse model of myocardial infarction.

HDL and apolipoprotein A1 (apoA1) concentrations inversely correlate with risk of death from ischemic heart disease; however, the role of apoA1 in the myocardial response to ischemia has not been well defined. To test whether apoA1, the primary HDL apolipoprotein, has an acute anti-inflammatory role in ischemic heart disease, we induced myocardial infarction via direct left anterior descending coronary artery ligation in apoA1 null (apoA1(-/-)) and apoA1 heterozygous (apoA1(+/-)) mice. We observed that apoA1(+/-) and apoA1(-/-) mice had a 52% and 125% increase in infarct size as a percentage of area at risk, respectively, compared with wild-type (WT) C57BL/6 mice. Mitochondrial oxidation contributes to tissue damage in ischemia-reperfusion injury. A substantial defect was present at baseline in the electron transport chain of cardiac myocytes from apoA1(-/-) mice localized to the coenzyme Q (CoQ) pool with impaired electron transfer (67% decrease) from complex II to complex III. Administration of coenzyme Q10 (CoQ10) to apoA1 null mice normalized the cardiac mitochondrial CoQ pool and reduced infarct size to that observed in WT mice. CoQ10 administration did not significantly alter infarct size in WT mice. These data identify CoQ pool content leading to impaired mitochondrial function as major contributors to infarct size in the setting of low HDL/apoA1. These data suggest a previously unappreciated mechanism for myocardial stunning, cardiac dysfunction, and muscle pain associated with low HDL and low apoA1 concentrations that can be corrected by CoQ10 supplementation and suggest populations of patients that may benefit particularly from CoQ10 supplementation.

(-)-Epigallocatechin-gallate (EGCG) stabilize the mitochondrial enzymes and inhibits the apoptosis in cigarette smoke-induced myocardial dysfunction in rats.

The present study brings out the preventive role of (-)-epigallocatechin-gallate (EGCG) on cardiac mitochondrial metabolism and apoptosis in cigarette smoke (CS)-exposed rats. The CS-exposed rats showed significantly decreased activities of TCA cycle enzymes and mitochondrial enzymatic antioxidants, on the other hand, mitochondrial lipid peroxidation was increased and GSH level was decreased. Further, CS exposure was found to induce cardiac apoptosis through release of cytochrome c into the cytosol, cleavage of pro-caspase-3 to active caspase-3, up-regulation of pro-apoptotic (Bax) and down-regulation of antiapoptotic (Bcl-2) molecules. The CS-induced apoptosis was further confirmed by mitochondrial and nuclear ultra structural apoptotic features as evaluated by electron microscopic studies. EGCG supplementation shelters the activities of TCA cycle enzymes and antioxidant enzymes, with concomitant decrease in lipid peroxidation and increase in GSH level. EGCG administration inhibited apoptosis through the inhibition of cytochrome c release into cytosol, activation of pro-caspase-3, down regulation of Bax and significant up regulation of Bcl-2. EGCG reversed the ultra structural apoptotic alterations of mitochondria and nucleus. The present study has provided experimental evidences that the EGCG treatment enduring to cardio protection at mitochondrial level.

Impaired mitochondrial biogenesis due to dysfunctional adiponectin-AMPK-PGC-1α signaling contributing to increased vulnerability in diabetic heart.

Impaired mitochondrial biogenesis causes skeletal muscle damage in diabetes. However, whether and how mitochondrial biogenesis is impaired in the diabetic heart remains largely unknown. Whether adiponectin (APN), a potent cardioprotective molecule, regulates cardiac mitochondrial function has also not been previously investigated. In this study, electron microscopy revealed significant mitochondrial disorders in ob/ob cardiomyocytes, including mitochondrial swelling and cristae disorientation and breakage. Moreover, mitochondrial biogenesis of ob/ob cardiomyocytes is significantly impaired, as evidenced by reduced Ppargc-1a/Nrf-1/Tfam mRNA levels, mitochondrial DNA content, ATP content, citrate synthase activity, complexes I/III/V activity, AMPK phosphorylation, and increased PGC-1α acetylation. Since APN is an upstream activator of AMPK and APN plasma levels are significantly reduced in ob/ob mice, we further tested the hypothesis that reduced APN in ob/ob mice is causatively related to mitochondrial biogenesis impairment. One week of APN treatment of ob/ob mice activated AMPK, reduced PGC-1α acetylation, increased mitochondrial biogenesis, and attenuated mitochondrial disorders. In contrast, knocking out APN inhibited AMPK-PGC-1α signaling and impaired both mitochondrial biogenesis and function. The ob/ob mice exhibited lower survival rates and exacerbated myocardial injury after MI, when compared to controls. APN supplementation improved mitochondrial biogenesis and attenuated MI injury, an effect that was almost completely abrogated by the AMPK inhibitor compound C. In high glucose/high fat treated neonatal rat ventricular myocytes, siRNA-mediated knockdown of PGC-1α blocked gAd-enhanced mitochondrial biogenesis and function and attenuated protection against hypoxia/reoxygenation injury. In conclusion, hypoadiponectinemia impaired AMPK-PGC-1α signaling, resulting in dysfunctional mitochondrial biogenesis that constitutes a novel mechanism for rendering diabetic hearts more vulnerable to enhanced MI injury.

Ganoderma lucidum ameliorate mitochondrial damage in isoproterenol-induced myocardial infarction in rats by enhancing the activities of TCA cycle enzymes and respiratory chain complexes.

BACKGROUND: Decreased mitochondrial function has been suggested to be one of the important pathological events in isoproterenol (ISO)-induced cardiotoxicity. In this communication, we have evaluated the protective effect of Ganoderma lucidum against ISO induced cardiac toxicity and mitochondrial dysfunction. METHODS: Cardiac toxicity was assessed by determining the activities of creatine kinase (CK) and lactate dehydrogenases (LDH) after subcutaneous injection of ISO (85 mg/kg) at an interval of 24h for 2 days. The animals were sacrificed 24h after last ISO administration. G. lucidum (100 and 250 mg/kg, p.o.) was given to the rats once daily for 15 days prior to the ISO challenge. Similarly, α-Tocopherol (100mg/kg, p.o) was kept as the standard. To assess the extent of cardiac mitochondrial damage, the activities of Krebs cycle dehydrogenases and mitochondrial complexes I, II, III, and IV as well as the level of ROS and mitochondrial membrane potential (ΔΨmt) were evaluated. RESULTS: Administration of G. lucidum and α-tocopherol significantly protected the elevated activities of CK and LDH. Further, the activities of mitochondrial enzymes and the level of ΔΨmt were significantly enhanced and the level of ROS was significantly declined in the G. lucidum and α-tocopherol treatments. CONCLUSION: The present study concluded that the cardiac mitochondrial enzymes are markedly declined by the ISO challenge and the administration G. lucidum and α-Tocopherol significantly protected mitochondria by preventing the decline of antioxidant status and ΔΨmt or by directly scavenging the free radicals.

Reduction of n-3 PUFAs, specifically DHA and EPA, and enhancement of peroxisomal beta-oxidation in type 2 diabetic rat heart.

BACKGROUND: There is overwhelming evidence that dietary supplementation with n-3 polyunsaturated fatty acids (PUFAs), mainly EPA (C20:5n-3) and DHA (C22:6n-3), has cardiovascular protective effects on patients with type 2 diabetes mellitus (T2DM) but not on healthy people. Because the T2DM heart increases fatty acid oxidation (FAO) to compensate for the diminished utilization of glucose, we hypothesize that T2DM hearts consume more n-3 PUFAs and, therefore, need more n-3 PUFAs. In the present study, we investigated the changes in cardiac n-3 PUFAs and peroxisomal beta-oxidation, which are responsible for the degradation of PUFAs in a high-fat diet (HFD) and low-dose streptozotocin- (STZ) induced type 2 diabetic rat model. METHODS AND RESULTS: The capillary gas chromatography results showed that all the n-3 (or omega-3) PUFAs, especially DHA (~50%) and EPA (~100%), were significantly decreased, and the n-6/n-3 ratio (~115%) was significantly increased in the hearts of diabetic rats. The activity of peroxisomal beta-oxidation, which is crucial to very-long-chain and unsaturated FA metabolism (including DHA), was significantly elevated in DM hearts. Additionally, the real-time PCR results showed that the mRNA expression of most peroxisomal beta-oxidation key enzymes were up-regulated in T2DM rat hearts, which might contribute to the reduction of n-3 (or omega-3) PUFAs. CONCLUSION: In conclusion, our results indicate that T2DM hearts consume more n-3 PUFAs, especially DHA and EPA, due to exaggerated peroxisomal beta-oxidation.

The disruption of mitochondrial metabolism and ion homeostasis in chicken hearts exposed to manganese.

Exposure to high levels of manganese (Mn) can result in cardiotoxicity in animals. However, little is known about the effect of excess Mn on poultry hearts. The aim of this study was to investigate the effect of dietary Mn on chicken cardiac injuries and the possible mechanisms of this process. In the present study, 400 fifty-day-old Hy-line brown cocks were randomly divided into four groups, and were fed either a commercial diet (containing 100mg/kg Mn) or a Mn-supplemented diet containing 600mg/kg, 900mg/kg, or 1800mg/kg Mn for 30, 60 or 90 days, respectively. Next, we examined several biomarkers of cardiac injury, including biochemical blood serum analyses, electrocardiogram assays, histological analyses, ultra-structural assays and apoptosis assays. To investigate the possible mechanisms of Mn-induced cardiotoxicity, we examined the effect of MnCl(2) on mitochondrial function and metal ion homeostasis. We found that subchronic MnCl(2) exposure induced damage in chicken hearts. Further investigations indicated that possible mechanisms for Mn-induced chicken cardiac injury included the disruption of mitochondrial metabolism and the alteration of ion homeostasis.

[Effects of ligustrazine on the mitochondrial structure and functions in the process myocardial hypertrophy].

OBJECTIVE: To explore changes of mitochondrial structure and functions, as well as the protection of ligustrazine in the process of myocardial hypertrophy. METHODS: Neonatal myocardial cells were isolated and cultured with angiotensin II (Ang II) for 72 or 96 h. The total protein content was detected using BCA method. The cell diameter was measured by inverted microscope, by which to reflect the proliferation situation of cardiomyocytes. The mitochondrial membrane potential (MMP) was measured by fluorescence microscope. The mitochondrial monoamine oxidase (MAO) activity was detected by spectrophotometer. The mitochondrial cytochrome oxidase (COX) activity and the mitochondrial damage percentage were detected by microplate reader, by which to reflect the damage of mitochondrial outer membrane's structure and the membranes' function. Also, cells were treated with ligustrazine and losartan and then the pharmacological effects on the mitochondrial structure and functions in the myocardial cells treated with Ang II were observed. RESULTS: At 72 h and 96 h, when compared with the blank group, cells treated with Ang II had increased total protein content (P < 0.01) and enlarged diameter (P < 0.01). Treated with Ang II, the MAO activity and the outer membrane damage percentage of myocardial cells significantly increased (P < 0.01), and mitochondrial COX activity and the mitochondrial MMP significantly decreased (P < 0.01). Compared with the model group at the same time period, ligustrazine significantly reduced myocardial cells' total protein content and myocardial cell diameter, and significantly decreased myocardial cells' MAO activity, increased mitochondrial COX activity, improved the outer membrane damage percentage and inner membrane MMP at 72 and 96 h, all showing statistical difference (P < 0.01, P < 0.05). CONCLUSIONS: During the process of myocardial hypertrophy existed the damage to the mitochondrial structure and functions. Ligustrazine protected the mitochondrial structure and functions of the myocardial cells in reversing Ang II induced myocardial cell hypertrophy.

Myocardial regulation of lipidomic flux by cardiolipin synthase: setting the beat for bioenergetic efficiency.

Lipidomic regulation of mitochondrial cardiolipin content and molecular species composition is a prominent regulator of bioenergetic efficiency. However, the mechanisms controlling cardiolipin metabolism during health or disease progression have remained elusive. Herein, we demonstrate that cardiac myocyte-specific transgenic expression of cardiolipin synthase results in accelerated cardiolipin lipidomic flux that impacts multiple aspects of mitochondrial bioenergetics and signaling. During the postnatal period, cardiolipin synthase transgene expression results in marked changes in the temporal maturation of cardiolipin molecular species during development. In adult myocardium, cardiolipin synthase transgene expression leads to a marked increase in symmetric tetra-18:2 molecular species without a change in total cardiolipin content. Mechanistic analysis demonstrated that these alterations result from increased cardiolipin remodeling by sequential phospholipase and transacylase/acyltransferase activities in conjunction with a decrease in phosphatidylglycerol content. Moreover, cardiolipin synthase transgene expression results in alterations in signaling metabolites, including a marked increase in the cardioprotective eicosanoid 14,15-epoxyeicosatrienoic acid. Examination of mitochondrial bioenergetic function by high resolution respirometry demonstrated that cardiolipin synthase transgene expression resulted in improved mitochondrial bioenergetic efficiency as evidenced by enhanced electron transport chain coupling using multiple substrates as well as by salutary changes in Complex III and IV activities. Furthermore, transgenic expression of cardiolipin synthase attenuated maladaptive cardiolipin remodeling and bioenergetic inefficiency in myocardium rendered diabetic by streptozotocin treatment. Collectively, these results demonstrate the unanticipated role of cardiolipin synthase in maintaining physiologic membrane structure and function even under metabolic stress, thereby identifying cardiolipin synthase as a novel therapeutic target to attenuate mitochondrial dysfunction in diabetic myocardium.