How oil breaks fish hearts

CHICAGO— Crude oil in the ocean from spills may cramp crucial electrical activity in fish, crippling the pitter-patter of piscine hearts and potentially causing death.

Researchers knew that spilled oil harms heart health of embryonic fish, but didn’t understand how oil sinks tickers.

Marine scientist Barbara Block of Stanford University and colleagues scooped up oil floating in the Gulf of Mexico from the 2010 Deepwater Horizon spill. They tested the oil’s toxicity on captive fish and on cardiac cells snagged from bluefin and yellowfin tuna.

The oil caused slow and irregular beats in heart cells, which can be fatal. It also disrupted electrical charges from ion channels, which act as passageways for ions to flow in and out of cells. Hydrocarbons in the oil may clog up the channels, which cells use to create electrical jolts and thump in sync. The researchers reported their results February 13 at the annual meeting of the American Association for the Advancement of Science and in the Feb. 14 Science.

Since the ion channels of fish hearts are similar to those in humans, the find may explain why exposure to petroleum-based air pollutants is linked to irregular heartbeats in people, the authors speculate.