An anterior view of the blood vessels of the upper body (Image: Medical RF.com / SPL)

After drinking a chemical dissolved in water, mice with damaged hearts turn from couch potatoes into treadmill tearaways, researchers say. The finding raises hopes that the same substance can invigorate patients weakened from heart attacks by increasing the supply of oxygen to damaged cardiac muscle.

Designed to make haemoglobin release more of its oxygen than normal, the drug, myo-inositol trispyrophosphate (ITPP) boosted exercise levels in the ailing mice by 35% when given dissolved in water. When given by injection into the abdomen, exercise levels rose a massive 60%.

“ITPP doesn’t deliver oxygen itself, but makes haemoglobin able to release a larger amount of oxygen to tissues,” explains Jean-Marie Lehn of the University of Strasbourg in France.


Normally, he says, haemoglobin releases only 25% of its oxygen cargo during one circuit of the body. But when ITPP binds to haemoglobin, it releases 35% more than usual, boosting supplies of oxygen to tissues without people having to inhale any extra air.

Sports warning

Further evidence of increased oxygen supply came from blood samples taken from the mice showing a fivefold reduction within just three days of hypoxia-inducible factor, a chemical distress signal produced by oxygen-starved tissue. The results also suggested that the effects from a single dose could last almost a week, so patients wouldn’t need to take ITPP every day.

Unlike artificial blood substitutes, which have run into practical and ethical problems during clinical trials, ITPP simply boosts the efficiency with which native blood supplies tissues with oxygen. It is also very similar to a naturally occurring chemical made in the body, myo-inositol.

As a result, Lehn hopes to begin clinical trials “as soon as possible”. For athletes tempted to use the substance to enhance performance, he warns: “It could be very easily detected.”

‘Novel approach’

Lehn says that studies are under way to find out exactly how ITPP interferes with haemoglobin to make it give up more oxygen. He says that the substance is not natural, but is related to myo-inositol, a substance found in rice and cereals.

Peter Weissberg, medical director of the British Heart Foundation, says that inadequate oxygen delivery to tissue causes many symptoms of heart failure. “Around 700,000 people in the UK alone are living with heart failure, and inadequate tissue oxygen delivery is the cause of many of the symptoms – particularly fatigue and poor exercise tolerance,” he says.

Such a novel approach is welcome, says Weissberg, given the limited success of existing treatments based on increasing heart output or improving blood circulation.

“They’ve found a molecule that can boost the amount of oxygen transferred from blood to the muscles,” he says. “If a similar effect can be achieved in [humans], it will raise the possibility of a new treatment to improve debilitating heart failure symptoms.”

Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0812381106)