Wednesday, 3 January, 2001, 19:19 GMT BBC
Spider calms the quaking heart
Venom from the tarantula spider could help prevent a common heart condition called atrial fibrillation.
Instead of beating normally and synchronously, fibrillating muscle in the heart's upper chambers (the atria) starts to quiver.
This may cause blood to pool and clot which can lead to further complications. Atrial fibrillation is thought to cause around 15% of strokes.
Now researchers at the State University of New York, US, have found a protein in the venom of certain spiders that could provide a novel drug treatment in the future.
"The heart contains receptors for mechanical input, which generate electrical currents," Professor Frederick Sachs told BBC News Online.
"There are about 10 billion cells in the heart and they're all excitable and they're all connected together. It's the electrical connections between them that normally synchronise the heart. Then, when there's a problem, they get unsynchronised."
The problem arises when heart tissue becomes stretched, either by disease or external trauma.
Mechanical changes in stretched heart tissue distort the receptors, generating random electrical signals, which in turn cause a chaotic twitching of the surrounding heart tissue.
Professor Sachs and his team set out to find a chemical that would quiet the random contractions. They found the answer - in the jaws of a spider.
A small protein in the venom of the Chilean Rosehair tarantula (Grammostola spatulata) blocks the rogue transmissions, bringing the fibrillation under control. Experiments with rabbit hearts have shown that in some cases the protein completely stops fibrillation.
Interestingly, the protein only works on stretched heart muscle. Even a massive dose has no effect on normal healthy heart tissue, which could mean a reduced risk of side effects.
"It's too good to be true, I didn't believe this was real science at first because it shouldn't be this good," said Professor Sachs.
The potential for a simple drug treatment for a common heart condition has already attracted the interest of several drug companies.
The research is published in the journal Nature.