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A Spider Bite That Soothes the Heart

WebMD Health News

Jan. 8, 2001 -- It's one of a handful of poisonous spiders that can really scare you to death. But researchers have now shown that an extract of the venom of the deadly tarantula spider can prevent the heart -- at least in rabbits -- from developing palpitations.

And scientists predict that the finding may mean that "atrial fibrillation," a potentially serious condition involving irregular, rapid heart beats, could be treated long before it begins to have damaging health effects. The common condition currently is treated with drugs that slow the heart rate, or with electrical shock to send an abnormally fast heartbeat back into a normal rhythm. But it remains a common cause of heart failure and stroke. Atrial fibrillation is often associated with stretching of the atrial, or upper chamber of the heart.

Reporting in this week's Nature, scientists looked at rabbits whose hearts had been provoked into atrial fibrillation and had been artificially stretched. They found that the abnormal heart rhythm could be suppressed when treated with the tarantula venom extract. What's causing the excitement is that as well as being highly effective, the extract, known as a peptide, does not appear to cause side effects in people with normal heart rhythms.

"The research shows that the peptide has no effect on a resting or unstretched heart, which means that side effects are, at least for the heart, probably not a serious problem," Frederick Sachs, PhD, professor of physiology and biophysics at State University of New York at Buffalo, tells WebMD. "We need to study the other organ systems in animals. But if, as we believe, side effects are minimal, we can readily make it into a useful drug."

"Atrial fibrillation is a common condition for which [available] treatments ... don't always work," Alison Shaw, cardiac nurse adviser at the British Heart Foundation, tells WebMD. "This new spider venom treatment is a novel approach that so far has only been performed on rabbit hearts. Widespread randomized trials on humans would be needed to evaluate its full potential."

The future of tarantula venom currently is the subject of negotiations with drug companies, according to Sachs, who carried out the research.

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