Word: blood
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Within hours of leaving the body, the research showed, a unit of blood loses up to 70% of its NO; by the time the blood reaches its "use by" expiration date 42 days later, the gas is almost nonexistent. "The reality is, we are giving patients blood that cannot deliver oxygen properly," says Stamler...
...consequences of this seem clear from the numbers. A study of 24,000 people with acute coronary symptoms showed that those who received a blood transfusion had a 25% chance of having a heart attack and an 8% chance of dying within 30 days; similar patients who did not get a transfusion had an 8% chance of a cardiac event and a 3% chance of death. Stamler believes that without NO, red blood cells are not dilating tiny vessels properly and instead pile up in the narrow passageways, blocking flow and damaging the very heart tissue the blood was transfused...
While donor blood alone may not be directly responsible for this added risk, those percentages had already been disturbing enough to persuade physicians to change what is known as their transfusion trigger. As a rule, they introduced donated blood as soon as the patient's hematocrit--a measure of the proportion of the blood made up of oxygen-carrying red cells--fell below the normal range of 45%-55%. Lately, however, they have begun waiting until it drops to less than 30% before transfusing...
Another answer may be to fix the blood that's on the shelves. Working with dogs, Stamler has shown that the heart-attack rate drops when depleted blood is replenished with liquid NO. Human premature babies born with underdeveloped lungs are already being exposed to gaseous NO to help their tissues get the oxygen they need. For now, the American Red Cross, which oversees the 14 million units of stored blood, is awaiting more studies before changing its processing and storage practices...
...their part, Stamler, who consults for a company developing NO-based therapies, and McMahon, whose work was funded in part by another such firm, are thinking about using transfusions of NO-fortified donor blood to treat such ills as heart disease, stroke and diabetes. "We want to open up blood vessels, and blood knows how to do that," he says. Perhaps a nitric oxide boost would help it do its job even better...