מתוך medicontext.co.il
WESTPORT, CT (Reuters Health) – Vitamin C appears to protect the vascular wall in patients with congestive heart failure (CHF) by preventing endothelial cell apoptosis, according to a European study team.
In a series of experiments, Dr. Stefanie Dimmeler, of the University of Frankfurt in Germany, and colleagues first showed that tumor necrosis factor-alpha (TNF-alpha) increased apoptosis in cultured endothelial cells by approximately threefold. This apoptosis was decreased by the addition of vitamin C to the cultures (p < 0.001). Similar results were seen in cells treated with angiotensin II.
Further work with the cultured cells, described in the October 30th issue of Circulation, showed that vitamin C interfered with apoptosis signaling by inhibiting the ability of TNF-alpha to induce cytochrome C release from the mitochondria and suppressing the activation of caspase-9.
The investigators randomly assigned 34 patients to treatment with vitamin C or placebo. Initial treatment was 2.5 g vitamin C or sodium chloride 0.9% administered intravenously for 10 minutes, followed by 3 days of 2 g vitamin C or placebo given orally twice daily.
Plasma levels of circulating apoptotic microparticles were reduced to 32% of baseline levels in patients receiving vitamin C, while levels in those treated with placebo were reduced by an insignificant amount, to 87% of baseline (p < 0.005).
When the researchers exposed cultured endothelial cells to subjects' serum, apoptosis was significantly reduced by serum from subjects treated with vitamin C compared with serum from subjects treated with placebo (p < 0.02).
However, vitamin C did not affect serum concentrations of TNF-alpha or other circulating cytokines. "Therefore, altered serum levels [of] circulating cytokines do not appear to contribute to the observed protective effect of vitamin C on endothelial cell apoptosis in CHF patients," Dr. Dimmeler's group writes.
In a journal statement, Dr. Dimmeler suggests that "the findings might contribute to our understanding of the mechanisms of heart failure progression and could add antioxidant treatment as a novel strategy to delay progression of heart failure."
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