scholarly journals Mitochondrial membrane potential in single living adult rat cardiac myocytes exposed to anoxia or metabolic inhibition.

1995 ◽  
Vol 486 (1) ◽  
pp. 1-13 ◽  
Author(s):  
F Di Lisa ◽  
P S Blank ◽  
R Colonna ◽  
G Gambassi ◽  
H S Silverman ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Cardiac Myocytes ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Metabolic Inhibition ◽  
Adult Rat ◽  
Rat Cardiac Myocytes ◽  
Single Living ◽  
Living Adult

scholarly journals Trimethylamine N-Oxide Does Not Impact Viability, ROS Production, and Mitochondrial Membrane Potential of Adult Rat Cardiomyocytes

2019 ◽  
Vol 20 (12) ◽  
pp. 3045 ◽  
Author(s):  
Querio ◽  
Antoniotti ◽  
Levi ◽  
Gallo
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Cellular Level ◽  
Cardiac Damage ◽  
Direct Role ◽  
Simultaneous Treatment ◽  
Rat Cardiomyocytes ◽  
Adult Rat ◽  
Affect Cell Viability

Trimethylamine N-oxide (TMAO) is an organic compound derived from dietary choline and L-carnitine. It behaves as an osmolyte, a protein stabilizer, and an electron acceptor, showing different biological functions in different animals. Recent works point out that, in humans, high circulating levels of TMAO are related to the progression of atherosclerosis and other cardiovascular diseases. However, studies on a direct role of TMAO in cardiomyocyte parameters are still limited. The purpose of this work is to study the effects of TMAO on isolated adult rat cardiomyocytes. TMAO in both 100 µM and 10 mM concentrations, from 1 to 24 h of treatment, does not affect cell viability, sarcomere length, intracellular ROS, and mitochondrial membrane potential. Furthermore, the simultaneous treatment with TMAO and known cardiac insults, such as H2O2 or doxorubicin, does not affect the treatment’s effect. In conclusion, TMAO cannot be considered a direct cause or an exacerbating risk factor of cardiac damage at the cellular level in acute conditions.

scholarly journals A digitized-fluorescence-imaging study of mitochondrial Ca2+ increase by doxorubicin in cardiac myocytes

1992 ◽  
Vol 281 (3) ◽  
pp. 871-878 ◽  
Author(s):  
E Chacon ◽  
R Ulrich ◽  
D Acosta
Keyword(s):  
Membrane Potential ◽  
Energy Conservation ◽  
Fluorescence Imaging ◽  
Cardiac Myocytes ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Cell Injury ◽  
Cultured Cells ◽  
Imaging Study

The objective of the present study was to investigate the role of mitochondrial Ca2+ in doxorubicin-induced cell injury. The effect of doxorubicin on cultured cells was investigated by digitized fluorescence imaging. The Ca2+ sensitive fluorescent dye fura-2 was used to estimate cytosolic, mitochondrial and total cellular Ca2+. Rhodamine 123 was used to estimate the mitochondrial membrane potential, and cellular ATP was determined by h.p.l.c. The data showed that doxorubicin induced greater-than-2-fold increases in mitochondrial Ca2+ before changes in cytosolic Ca2+ could be detected. An increase in mitochondrial Ca2+ paralleled the observed dissipation in mitochondrial membrane potential. Cellular ATP levels appeared to decrease as a result of mitochondrial dysfunction, which in turn produced greater-than-2-fold increases in cytosolic Ca2+. The data suggest that doxorubicin-induced alterations in mitochondrial Ca2+ homoeostasis are associated with a dissipation in energy conservation, which may result in cell injury.

scholarly journals Expression of the mitochondrial calcium uniporter in cardiac myocytes improves impaired mitochondrial calcium handling and metabolism in simulated hyperglycemia

2016 ◽  
Vol 311 (6) ◽  
pp. C1005-C1013 ◽  
Author(s):  
Julieta Diaz-Juarez ◽  
Jorge Suarez ◽  
Federico Cividini ◽  
Brian T. Scott ◽  
Tanja Diemer ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Membrane Potential ◽  
Cardiac Myocytes ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Calcium Handling ◽  
Acid Oxidation ◽  
Mitochondrial Calcium ◽  
Pathophysiological Mechanism ◽  
Protein Levels

Diabetic cardiomyopathy is associated with metabolic changes, including decreased glucose oxidation (Gox) and increased fatty acid oxidation (FAox), which result in cardiac energetic deficiency. Diabetic hyperglycemia is a pathophysiological mechanism that triggers multiple maladaptive phenomena. The mitochondrial Ca2+ uniporter (MCU) is the channel responsible for Ca2+ uptake in mitochondria, and free mitochondrial Ca2+ concentration ([Ca2+]m) regulates mitochondrial metabolism. Experiments with cardiac myocytes (CM) exposed to simulated hyperglycemia revealed reduced [Ca2+]m and MCU protein levels. Therefore, we investigated whether returning [Ca2+]m to normal levels in CM by MCU expression could lead to normalization of Gox and FAox with no detrimental effects. Mouse neonatal CM were exposed for 72 h to normal glucose [5.5 mM glucose + 19.5 mM mannitol (NG)], high glucose [25 mM glucose (HG)], or HG + adenoviral MCU expression. Gox and FAox, [Ca2+]m, MCU levels, pyruvate dehydrogenase (PDH) activity, oxidative stress, mitochondrial membrane potential, and apoptosis were assessed. [Ca2+]m and MCU protein levels were reduced after 72 h of HG. Gox was decreased and FAox was increased in HG, PDH activity was decreased, phosphorylated PDH levels were increased, and mitochondrial membrane potential was reduced. MCU expression returned these parameters toward NG levels. Moreover, increased oxidative stress and apoptosis were reduced in HG by MCU expression. We also observed reduced MCU protein levels and [Ca2+]m in hearts from type 1 diabetic mice. Thus we conclude that HG-induced metabolic alterations can be reversed by restoration of MCU levels, resulting in return of [Ca2+]m to normal levels.

scholarly journals Regulation of mitochondrial morphology and function by O-GlcNAcylation in neonatal cardiac myocytes

2011 ◽  
Vol 300 (6) ◽  
pp. R1296-R1302 ◽  
Author(s):  
Ayako Makino ◽  
Jorge Suarez ◽  
Thomas Gawlowski ◽  
Wenlong Han ◽  
Hong Wang ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Cardiac Myocytes ◽  
Mitochondrial Membrane Potential ◽  
High Glucose ◽  
Mitochondrial Membrane ◽  
Control Level ◽  
Mitochondrial Morphology ◽  
Cell Physiology ◽  
Mitochondrial Fragmentation ◽  
Complex Iv

Mitochondria are crucial organelles in cell life serving as a source of energy production and as regulators of Ca2+ homeostasis, apoptosis, and development. Mitochondria frequently change their shape by fusion and fission, and recent research on these morphological dynamics of mitochondria has highlighted their role in normal cell physiology and disease. In this study, we investigated the effect of high glucose on mitochondrial dynamics in neonatal cardiac myocytes (NCMs). High-glucose treatment of NCMs significantly decreased the level of optical atrophy 1 (OPA1) (mitochondrial fusion-related protein) protein expression. NCMs exhibit two different kinds of mitochondrial structure: round shape around the nuclear area and elongated tubular structures in the pseudopod area. High-glucose-treated NCMs exhibited augmented mitochondrial fragmentation in the pseudopod area. This effect was significantly decreased by OPA1 overexpression. High-glucose exposure also led to increased O-GlcNAcylation of OPA1 in NCMs. GlcNAcase (GCA) overexpression in high-glucose-treated NCMs decreased OPA1 protein O-GlcNAcylation and significantly increased mitochondrial elongation. In addition to the morphological change caused by high glucose, we observed that high glucose decreased mitochondrial membrane potential and complex IV activity and that OPA1 overexpression increased both levels to the control level. These data suggest that decreased OPA1 protein level and increased O-GlcNAcylation of OPA1 protein by high glucose lead to mitochondrial dysfunction by increasing mitochondrial fragmentation, decreasing mitochondrial membrane potential, and attenuating the activity of mitochondrial complex IV, and that overexpression of OPA1 and GCA in cardiac myocytes may help improve the cardiac dysfunction in diabetes.

Increased [Mg2+]oreduces Ca2+ influx and disruption of mitochondrial membrane potential during reoxygenation

2001 ◽  
Vol 281 (5) ◽  
pp. H2113-H2123 ◽  
Author(s):  
Mohammad Nouri Sharikabad ◽  
Kirsten Margrethe Østbye ◽  
Odd Brørs
Keyword(s):  
Flow Cytometry ◽  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Inverse Correlation ◽  
Protective Effects ◽  
Influx Rate ◽  
Rat Cardiomyocytes ◽  
Adult Rat ◽  
Sarcoplasmatic Reticulum

Increase in extracellular Mg2+concentration ([Mg2+]o) reduces Ca2+ accumulation during reoxygenation of hypoxic cardiomyocytes and exerts protective effects. The aims of the present study were to investigate the effect of increased [Mg2+]o on Ca2+ influx and efflux, free cytosolic Ca2+([Ca2+]i) and Mg2+ concentrations ([Mg2+]i), Ca2+ accumulation in the presence of inhibitors of mitochondrial or sarcoplasmatic reticulum Ca2+ transport, and finally mitochondrial membrane potential (Δψm). Isolated adult rat cardiomyocytes were exposed to 1 h of hypoxia and subsequent reoxygenation. Cell Ca2+ was determined by 45Ca2+uptake, and the levels of [Mg2+]i and [Ca2+]i were determined by flow cytometry as the fluorescence of magnesium green and fluo 3, respectively. Ca2+ influx rate was significantly reduced by ∼40%, whereas Ca2+ efflux was not affected by increased [Mg2+]o (5 mM) during reoxygenation. [Ca2+]i and [Mg2+]iwere increased at the end of hypoxia, fell after reoxygenation, and were unaffected by increased [Mg2+]o. Clonazepam, a selective mitochondrial Na+/Ca2+exchange inhibitor (100 μM), significantly reduced Ca2+accumulation by 70% and in combination with increased [Mg2+]o by 90%. Increased [Mg2+]o, clonazepam, and the combination of both attenuated the hypoxia-reoxygenation-induced reduction in Δψm, determined with the cationic dye JC-1 by flow cytometry. A significant inverse correlation was observed between Δψm and cell Ca2+ in reoxygenated cells treated with increased [Mg2+]o and clonazepam. In conclusion, increased [Mg2+]o(5 mM) inhibits Ca2+ accumulation by reducing Ca2+ influx and preserves Δψm without affecting [Ca2+]i and [Mg2+]i during reoxygenation. Preservation of mitochondria may be an important effect whereby increased [Mg2+]o protects the postischemic heart.

DNA damage is an early event in doxorubicin-induced cardiac myocyte death

2006 ◽  
Vol 291 (3) ◽  
pp. H1273-H1280 ◽  
Author(s):  
Thomas L'Ecuyer ◽  
Sanjeev Sanjeev ◽  
Ronald Thomas ◽  
Raymond Novak ◽  
Lauri Das ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Membrane Potential ◽  
Cardiac Myocytes ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Cardiac Myocyte ◽  
Dna Lesions ◽  
Doxorubicin Treatment ◽  
P53 Activation

Anthracyclines are antitumor agents the main clinical limitation of which is cardiac toxicity. The mechanism of this cardiotoxicity is thought to be related to generation of oxidative stress, causing lethal injury to cardiac myocytes. Although protein and lipid oxidation have been documented in anthracycline-treated cardiac myocytes, DNA damage has not been directly demonstrated. This study was undertaken to determine whether anthracyclines induce cardiac myocyte DNA damage and whether this damage is linked to a signaling pathway culminating in cell death. H9c2 cardiac myocytes were treated with the anthracycline doxorubicin at clinically relevant concentrations, and DNA damage was assessed using the alkaline comet assay. Doxorubicin induced DNA damage, as shown by a significant increase in the mean tail moment above control, an effect ameliorated by inclusion of a free radical scavenger. Repair of DNA damage was incomplete after doxorubicin treatment in contrast to the complete repair observed in H2O2-treated myocytes after removal of the agent. Immunoblot analysis revealed that p53 activation occurred subsequent in time to DNA damage. By a fluorescent assay, doxorubicin induced loss of mitochondrial membrane potential after p53 activation. Chemical inhibition of p53 prevented doxorubicin-induced cell death and loss of mitochondrial membrane potential without preventing DNA damage, indicating that DNA damage was proximal in the events leading from doxorubicin treatment to cardiac myocyte death. Specific doxorubicin-induced DNA lesions included oxidized pyrimidines and 8-hydroxyguanine. DNA damage therefore appears to play an important early role in anthracycline-induced lethal cardiac myocyte injury through a pathway involving p53 and the mitochondria.

The prolyl hydroxylase oxygen-sensing pathway is cytoprotective and allows maintenance of mitochondrial membrane potential during metabolic inhibition

2007 ◽  
Vol 292 (2) ◽  
pp. C719-C728 ◽  
Author(s):  
Vijayalakshmi Sridharan ◽  
Jason Guichard ◽  
Rachel M. Bailey ◽  
Harinath Kasiganesan ◽  
Craig Beeson ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Oxygen Sensor ◽  
Oxygen Sensing ◽  
Prolyl Hydroxylase ◽  
Metabolic Inhibition ◽  
Atp Depletion ◽  
Atp Levels

The cellular oxygen sensor is a family of oxygen-dependent proline hydroxylase domain (PHD)-containing enzymes, whose reduction of activity initiate a hypoxic signal cascade. In these studies, prolyl hydroxylase inhibitors (PHIs) were used to activate the PHD-signaling pathway in cardiomyocytes. PHI-pretreatment led to the accumulation of glycogen and an increased maintenance of ATP levels in glucose-free medium containing cyanide. The addition of the glycolytic inhibitor 2-deoxy-d-glucose (2-DG) caused a decline of ATP levels that was indistinguishable between control and PHI-treated myocytes. Despite the comparable levels of ATP depletion, PHI-preconditioned myocytes remained significantly protected. As expected, mitochondrial membrane potential (ΔΨmito) collapses in control myocytes during cyanide and 2-DG treatment and it fails to completely recover upon washout. In contrast, ΔΨmito is partially maintained during metabolic inhibition and recovers completely on washout in PHI-preconditioned cells. Inclusion of rotenone, but not oligomycin, with cyanide and 2-DG was found to collapse ΔΨmito in PHI-pretreated myocytes. Thus, continued complex I activity was implicated in the maintenance of ΔΨmito in PHI-treated myocytes, whereas a role for the “reverse mode” operation of the F1F0-ATP synthase was ruled out. Further examination of mitochondrial function revealed that PHI treatment downregulated basal oxygen consumption to only ∼15% that of controls. Oxygen consumption rates, although initially lower in PHI-preconditioned myocytes, recovered completely upon removal of metabolic poisons, while reaching only 22% of preinsult levels in control myocytes. We conclude that PHD oxygen-sensing mechanism directs multiple compensatory changes in the cardiomyocyte, which include a low-respiring mitochondrial phenotype that is remarkably protected against metabolic insult.

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