Storage Lesion in Banked Blood Due to Disruption of Nitric Oxide (NO) Homeostasis

The increased storage time of transfused blood is associated with an increased risk of cardiovascular events and organ failure. The underlying biological mechanism as to why this happens is not understood. A major abnormality in aged blood is the reduced life span of red blood cells after they are infused. This is associated with rupture of the red blood cells and release of their contents. However, the degree of red blood cell rupture and release of the cell's contents in humans after transfusion has not been well studied. It has been seen that even low levels of red blood cell rupture severely decrease the amount of nitric oxide and other factors that effect how blood vessels function. The purpose of this study is to perform human forearm blood flow studies to evaluate wether there are a sufficient amount these factors released during red blood transfusion to significantly affect how blood vessel function in humans. This study will enroll normal healthy volunteers between 18 to 50 years of age. 500 ml (1.0 unit) of blood will be collected from subjects who will then return in 5-10 days and be re-infused with the blood 5-10 days after storage.The subjects will return after 25-37 days and be infused with blood 35-42 days after storage. The study will use a tool called strain gauge plethysmography and the drug acetylcholine to measure the effect of fresh (i.e., 5-10 days) versus aged (35-42 days) autologous blood transfusions on forearm blood flow in healthy volunteers.