According to a report by two research teams in this week's online edition of Proceedings of the National Academy of Sciences, the donated blood can also do more harm than good as it begins to lose a key gas within three hours of it being donated.
Researchers from Duke University Medical Center believe that the new discovery would help doctors find reasons to the frequency of heart attack and stroke in patients receiving transfusions.
A number of recent studies have found that patients who receive blood transfusions have higher incidences of heart attack, heart failure, stroke and even death.
If the blood vessels fail to relax and constrict, it can hinder the blood flow to the cells. Nitric oxide opens up blood vessels, allowing red blood cells to deliver oxygen. If the red blood cells back up in the vessel and tissues go without oxygen, it results in heart attack or even death.
Dr. Jonathan Stamler of Duke University, leader of one of the research groups said, "It doesn't matter how much oxygen is being carried by red blood cells, it cannot get to the tissues that need it without nitric oxide."
"In principle, we now have a solution to the nitric oxide problem -- we can put it back -- but it needs to be proven in a clinical trial," he added.
Researchers have carried out various experiments in animals to increase blood flow to the hearts by adding nitric oxide back to banked blood. Further research is need to see if this technique also works in humans.
