Cellular and mitochondrial mechanisms of atrial fibrillation

AbstractThe molecular mechanisms underlying atrial fibrillation (AF), the most common form of arrhythmia, are poorly understood and therefore target-specific treatment options remain an unmet clinical need. Excitation–contraction coupling in cardiac myocytes requires high amounts of adenosine triphosphate (ATP), which is replenished by oxidative phosphorylation in mitochondria. Calcium (Ca2+) is a key regulator of mitochondrial function by stimulating the Krebs cycle, which produces nicotinamide adenine dinucleotide for ATP production at the electron transport chain and nicotinamide adenine dinucleotide phosphate for the elimination of reactive oxygen species (ROS). While it is now well established that mitochondrial dysfunction plays an important role in the pathophysiology of heart failure, this has been less investigated in atrial myocytes in AF. Considering the high prevalence of AF, investigating the role of mitochondria in this disease may guide the path towards new therapeutic targets. In this review, we discuss the importance of mitochondrial Ca2+ handling in regulating ATP production and mitochondrial ROS emission and how alterations, particularly in these aspects of mitochondrial activity, may play a role in AF. In addition to describing research advances, we highlight areas in which further studies are required to elucidate the role of mitochondria in AF.

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Role of the C-Terminal Tyrosine of Ferredoxin-Nicotinamide Adenine Dinucleotide Phosphate Reductase in the Electron Transfer Processes with Its Protein Partners Ferredoxin and Flavodoxin†

Biochemistry ◽

10.1021/bi049858h ◽

2004 ◽

Vol 43 (20) ◽

pp. 6127-6137 ◽

Cited By ~ 42

Author(s):

Isabel Nogués ◽

Jesús Tejero ◽

John K. Hurley ◽

Darío Paladini ◽

Susana Frago ◽

...

Keyword(s):

Electron Transfer ◽

Nicotinamide Adenine Dinucleotide ◽

Nicotinamide Adenine Dinucleotide Phosphate ◽

Nicotinamide Adenine ◽

Transfer Processes ◽

Protein Partners ◽

Electron Transfer Processes

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Serum levels of nicotinamide-adenine dinucleotide phosphate oxidase 4 are associated with non-valvular atrial fibrillation

Biomedical Reports ◽

10.3892/br.2015.504 ◽

2015 ◽

Vol 3 (6) ◽

pp. 864-868 ◽

Cited By ~ 8

Author(s):

TONG LIU ◽

QINGMIAO SHAO ◽

PANAGIOTIS KORANTZOPOULOS ◽

ENZHAO LIU ◽

GANG XU ◽

...

Keyword(s):

Atrial Fibrillation ◽

Nicotinamide Adenine Dinucleotide ◽

Nicotinamide Adenine Dinucleotide Phosphate ◽

Serum Levels ◽

Nicotinamide Adenine

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NAD(P)H oxidase–dependent platelet superoxide anion release increases platelet recruitment

Blood ◽

10.1182/blood.v100.3.917 ◽

2002 ◽

Vol 100 (3) ◽

pp. 917-924 ◽

Cited By ~ 183

Author(s):

Florian Krötz ◽

Hae Young Sohn ◽

Torsten Gloe ◽

Stefan Zahler ◽

Tobias Riexinger ◽

...

Keyword(s):

Nicotinamide Adenine Dinucleotide ◽

Thrombus Formation ◽

Nicotinamide Adenine Dinucleotide Phosphate ◽

Human Platelets ◽

Nicotinamide Adenine ◽

Irreversible Aggregation ◽

Reduced Nicotinamide Adenine Dinucleotide ◽

Specific Peptide

Abstract Platelets, although not phagocytotic, have been suggested to release O2−. Since O2−-producing reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) oxidases can be specifically activated by certain agonists and are found in several nonphagocytotic tissues, we investigated whether such an enzyme is the source of platelet-derived O2−. We further studied which agonists cause platelet O2−release and whether platelet-derived O2− influences thrombus formation in vitro. Collagen, but not adenosine 5′-diphosphate (ADP) or thrombin, increased O2− formation in washed human platelets. This was a reduced nicotinamide adenine dinucleotide (NADH)–dependent process, as shown in platelet lysates. Consistent with a role of a platelet, NAD(P)H oxidase expression of its subunits p47phox and p67phoxand inhibition of platelet O2− formation by diphenylene-iodoniumchloride (DPI) and by the specific peptide-antagonist gp91ds-tat were observed. Whereas platelet-derived O2− did not influence initial aggregation, platelet recruitment to a preformed thrombus following collagen stimulation was significantly attenuated by superoxide dismutase (SOD) or DPI. It was also inhibited when ADP released during aggregation was cleaved by the ectonucleotidase apyrase. ADP in supernatants of collagen-activated platelets was decreased in the presence of SOD, resulting in lower ADP concentrations available for recruitment of further platelets. Exogenous O2−increased ADP- concentrations in supernatants of collagen-stimulated platelets and induced irreversible aggregation when platelets were stimulated with otherwise subthreshold concentrations of ADP. These results strongly suggest that collagen activation induces NAD(P)H oxidase–dependent O2− release in platelets, which in turn enhances availability of released ADP, resulting in increased platelet recruitment.

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