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Hypoxia studied, protective role of vitamin C defined



According to recent research from the United States, hypoxia-reoxygenation-induced mitochondrial damage and apoptosis in human endothelial cells are inhibited by vitamin C.

"Hypoxia and hypoxia-reperfusion (H-R) play important roles in human pathophysiology because they occur in clinical conditions such as circulatory shock, myocardial ischemia, stroke, and organ transplantation," wrote M. Dharma-Scareno and colleagues, Memorial Sloan-Kettering Cancer Center.

"Reintroduction of oxygen to hypoxic cells during reperfusion causes an increase in generation of reactive oxygen species (ROS), which can alter cell signaling, and cause damage to lipids, proteins, and DNA leading to ischemia-reperfusion injury.

"Since vitamin C is a potent antioxidant and quenches ROS, we investigated the role of intracellular ascorbic acid (iAA) in endothelial cells undergoing hypoxia-reperfusion," the investigators explained.

"Intracellular AA protected human endothelial cells from H-R-induced apoptosis. Intracellular AA also prevented loss of mitochondrial membrane potential and the release of cytochrome C and activation of caspase-9 and caspase-3 during H-R.

"Additionally," continued the authors, "inhibition of caspase-9 activation prevented H-R-induced apoptosis, suggesting a mitochondrial site of initiation of apoptosis. We found that H-R induced an increase in ROS in endothelial cells that was abrogated in the presence of iAA.

"Our results indicate that vitamin C prevents hypoxia and H-R-induced damage to human endothelium," concluded the researchers.

Dharma-Scareno and colleagues published their study in Free Radical Biology and Medicine (Hypoxia-reoxygenation-induced mitochondrial damage and apoptosis in human endothelial cells are inhibited by vitamin C. Free Radic Biol Med, 2005;38(10):1311-1322).

For additional information, contact M. Dharma-Scareno, Memorial Sloan-Kettering Cancer Center, Molecular Pharmacology & Chemistry Program, 1275 York Avenue, New York City, NY 10021, USA.

Publisher contact information for the journal Free Radical Biology and Medicine is: Pergamon-Elsevier Science Ltd., the Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, England.

Keywords: New York City, New York, United States, Angiology, Apoptosis, Dehydroascorbic Acid, Diet and Nutrition, Endothelium, Free Radicals, Hypoxia, Hypoxia Reoxygenation, Mitochondria, Reactive Oxygen Species, Vitamin C. This article was prepared by Biotech Week editors from staff and other reports. Copyright 2005, Biotech Week via NewsRx.com.

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