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Last Updated: Thursday, 25 March, 2004, 00:03 GMT
Pill 'could prevent the bends'
The bends can be fatal
Scientists believe a pill could be developed to prevent divers getting the bends.

Combining exercise prior to diving with a pill releasing nitric oxide (NO) would allow longer or deeper dives.

New Scientist magazine reports the Norwegian researchers are confident the drug would reduce the number of harmful bubbles that form in the blood.

However, sub-aqua experts warned the side-effects of any drug would have to be carefully examined.

The research team at the Norwegian University of Science and Technology in Trondheim previously carried out tests on rats, which found intense exercise around 20 hours before a simulated dive in a pressure chamber significantly reduced nitrogen bubble formation.

Appropriately timed exercise and a nitric oxide-releasing agent may form the basis of a new approach to preventing serious decompression sickness
Ulrik Wisloff, Norwegian University of Science and Technology
Nitrogen dissolves in the blood during dives, but comes out of solution if divers return to normal pressure too rapidly and this can cause the bends, or decompression sickness.

It is thought exercise works by eliminating microbubbles, or nuclei, that lead to the formation of larger bubbles in the blood.

Other studies have suggested the microbubbles attach to the walls of blood vessels, and exercise is known to stimulate the release of nitric oxide, dilating the blood vessels and changing their surface properties.

The Norwegian team therefore carried out further research on rats, published in the Journal of Physiology, which combined exercise with nitric oxide-releasing agents given for five days and then 20 hours prior to diving.

This significantly reduced bubble formation and prevented death.

Ulrik Wisloff and fellow researchers concluded: "The findings of a protective effect against the bubble formation and death by appropriately timed exercise and an NO-releasing agent may form the basis of a new approach to preventing serious decompression sickness."


Mike Clack, techinical adviser at the British Sub-Aqua Club, said anything that added to the methods available to deal with decompression sickness was to be welcomed.

But he added: "The diver should ensure that any drug used while diving would have no effect on them while breathing under pressure."

Dr Rachel Broadley, a hyerbaric physician at the Diving Diseases and Research Centre in Plymouth, described the research as "very exciting".

She said: "If you inhibit the synthesis of nitric oxide, it appears to predispose to more bubbles being formed. By opposing that, you can prevent it. But how it would be done is very difficult to say."

She warned that nitric oxide can alter how the cardiovascular system works under diving conditions.

There were also problems associated with the use of exercise because of the precise timing needed.

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