Something fishy about frozen livers.

The same proteins that keep cold-water fish from freezing may extend the life of donor organs awaiting transplantation, says Boris Rubinsky, a biomedical engineer at the University of California, Berkeley.

On March 11, Rubinsky told a U.C.-Berkeley Industrial Liaison Program Conference that he and his co-workers added proteins from the Newfoundland ocean pout to "the worst possible preserving solution" and used this mixture to keep a rat liver frozen for 24 hours without causing severa damage. Livers receiving the fish proteins functioned three times better than livers not receiving the proteins, he says.

Cold temperatures damages cells by impairing their ability to maintain a proper ion balance, says Rubinsky. Normally, cells maintain this balance by pumping ions in and out through holes called ion channels. However, as temperatures reach the freezing point, the pumping slows, eventually allowing a lethal amount of ions to build up inside.

Current preserving solutions attempt to maintain an ion balance as temperatures drop by mimicking the cell's internal chemical composition. However, since chemical changes occur constantly inside the cell, no solution can perfectly match this internal mixture, says Rubinsky.

Although researchers discovered two decades ago that certain proteins inside fish - dubbed "antifreeze" proteins - keep them from freezing, little is known about how these compounds work. However, in a follow-up to his liver experiment, Rubinsky and his co-workers uncovered a possible solution to the mystery.

The researchers found that antifreeze proteins plug ion channels when the temperature drops, allowing the cell to maintain its proper ion balance. This explains how the frozen rat liver stayed so healthy, says Rubinsky. The finding appears in the March AMERICAN JOURNAL OF PHYSIOLOGY.