Science News - BPA In Parts-Per-Trillion Concentrations Can Cause Heart Cells To "Misfire"
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That’s small consolation, says Laura Vandenberg of Tufts University in Medford, Mass.: In the new BPA study, “the most effective dose was very close to — if not completely overlapping — what’s been reported in humans,” she says.
Parts-per-trillion concentrations of BPA triggered heart-muscle cells to begin beating to their own internal drummers. These cells should instead hold off beating until they receive signals from a central pacemaker, explains Hong-Sheng Wang of the University of Cincinnati College of Medicine, whose team conducted the new study. The resulting arrhythmia, known as fibrillation, caused by unsynchronized beating can trigger sudden cardiac death, Wang says.
BPA mimics the hormone estrogen in the body. In 2009, the Cincinnati team showed that both estrogen and BPA could alter contraction rates in heart cells — but only those from female animals. The researchers recently linked this finding to estrogen’s effect on calcium, which plays a pivotal role in heart-cell contractions. Both estrogen and BPA — especially together — fostered a leakiness of calcium within female heart cells, the team reported in the Sept. 27 PLoS ONE.
Those researchers have now linked this gender-specific effect to cell-surface estrogen sensors that come in two flavors: alpha and beta. Triggering the beta sensors when a cell is stressed stimulates inappropriate autonomous cell contractions, Wang’s team reports online in the February 2012 Endocrinology. Alpha sensors inhibit such activity. Differences in the ratio of alpha sensors to beta sensors on a cell — and probably the absolute number available to pick up signals — may explain gender-specific vulnerability to arrhythmia, Wang says.
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http://www.sciencenews.org/view/generic/id/337035/title/BPA_sends_false_signals_to_female_hearts
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