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Updated: 03/13/2014 02:59:25PM

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Oil spill gives fish heart attacks

Scientists have cracked a cellular biology mystery underlying a harmful effect oil spills have on fish: Irregular heartbeats that can lead to cardiac arrest. In studying the effects of the 2010 Deepwater Horizon oil spill on bluefin tuna spawning in the Gulf of Mexico, the research team discovered that polycyclic aromatic hydrocarbons, or PAHs, block “signaling pathways” that allow potassium and calcium ions to flow in and out of cardiac cell membranes and sustain normal heart rates. Even very low concentrations of crude oil can disrupt these signaling pathways, slowing the pace of heartbeats, the researchers reported last week in the journal Science. Their study also suggests that PAH cardiotoxicity was potentially a common form of injury among a broad range of species in the vicinity of the oil spilled into one of the most productive ocean ecosystems in the world. Study leader Barbara Block, a professor of marine sciences at Stanford University, said future research should be extended to include mammals and humans because the signaling pathways of their cardiac cells are similar to those of tuna, and PAHs are found in coal tar, creosote, air pollution and urban runoff. “This raises the possiblity that exposure to environmental PAHs in many animals — including humans — could lead to cardiac arrhythmias and bradycardia, or slowing of the heart,” Block said.

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