guanosine-triphosphate and 3-nitrotyrosine

Excess catecholamine levels are suggested to be cardiotoxic and to underlie stress-induced heart failure. The cardiotoxic effects of norepinephrine and epinephrine are well recognized. However, although cardiac and circulating dopamine levels are also increased in stress cardiomyopathy patients, knowledge regarding putative toxic effects of excess dopamine levels on cardiomyocytes is scarce. We now studied the effects of elevated dopamine levels in H9c2 cardiomyoblasts. H9c2 cells were cultured and treated with dopamine (200 μM) for 6, 24, and 48 h. Subsequently, the effects on lipid accumulation, cell viability, flippase activity, reactive oxygen species (ROS) production, subcellular NADPH oxidase (NOX) protein expression, and ATP/ADP and GTP/GDP levels were analyzed. Dopamine did not result in cytotoxic effects after 6 h. However, after 24 and 48 h dopamine treatment induced a significant increase in lipid accumulation, nitrotyrosine levels, indicative of ROS production, and cell death. In addition, dopamine significantly reduced flippase activity and ATP/GTP levels, coinciding with phosphatidylserine exposure on the outer plasma membrane. Furthermore, dopamine induced a transient increase in cytoplasmic and (peri)nucleus NOX1 and NOX4 expression after 24 h that subsided after 48 h. Moreover, while dopamine induced a similar transient increase in cytoplasmic NOX2 and p47

Topics: Adenosine Diphosphate; Adenosine Triphosphate; Animals; Caspase 3; Cell Line; Cell Membrane; Cell Survival; Dopamine; Dopamine Agents; Flow Cytometry; Guanosine Diphosphate; Guanosine Triphosphate; Hydrogen-Ion Concentration; Inflammation; Lipid Metabolism; Microscopy, Electron; Microscopy, Fluorescence; Myoblasts, Cardiac; NADH, NADPH Oxidoreductases; NADPH Oxidase 1; NADPH Oxidase 4; NADPH Oxidases; Nuclear Proteins; Oxidative Stress; Peroxidase; Rats; Reactive Oxygen Species; Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins; Tyrosine

Green tea polyphenols (GTP) are thought to help prevent oxidative stress-related diseases, such as cancer, cardiovascular disease, neurodegenerative disease, and aging. We here investigate the protective mechanisms of GTP on SH-SY5Y cells against apoptosis induced by the pro-parkinsonian neurotoxin 6-hydroxydopamine (6-OHDA). GTP rescued the changes in condensed nuclear and apoptotic bodies, attenuated 6-OHDA-induced early apoptosis, prevented the decrease in mitochondrial membrane potential, and suppressed accumulation of reactive oxygen species (ROS) and of intracellular free Ca(2+). GTP also counteracted the 6-OHDA-induced nitric oxide increase and overexpression of nNOS and iNOS, and decreased the level of protein-bound 3-nitrotyrosine (3-NT). In addition, GTP inhibited the autooxidation of 6-OHDA and scavenged oxygen free radicals in a dose- and time-dependent manner. Our results show that the protective effects of GTP on SH-SY5Y cells are mediated, at least in part, by controlling the ROS-NO pathway.

Topics: Annexin A5; Apoptosis; Blotting, Western; Calcium; Cell Line, Tumor; Cell Survival; Coloring Agents; Dose-Response Relationship, Drug; Flavonoids; Flow Cytometry; Free Radicals; Guanosine Triphosphate; Humans; Membrane Potentials; Mitochondria; Models, Biological; Neurons; Nitric Oxide; Oxidopamine; Oxygen; Parkinson Disease; Phenols; Polyphenols; Quinones; Reactive Oxygen Species; Tea; Tetrazolium Salts; Thiazoles; Time Factors; Tyrosine