Sanne de Bruin

16 Chapter 1 tive oxygen species. The optimal pH of glucose-6-phosphate dehydrogenase (G6PD), the rate limiting enzyme of the PPP is 7.8 42 . After 35 days of storage, G6PD activity was found to be decreased in SAGM stored RBCs 43 . These RBCs might be more vulnerable to oxidative stress. The reversibility of the metabolic changes after transfusion into the recipient is not complete known. A fewmetabolites have been assessed after transfusion, including ATP and 2,3-DPG levels. They showed recovery in approximately 72 hours after transfusion 44 . Assessing the metabolic recovery over time after transfusion, could give more insight in how storage of RBCs could be further optimized. To reduce the storage lesion, several additive solutions have been developed. Themech- anism of action is that chloride-free additive solutions induce a shift of the intracellular chloride into the extracellular department (Figure 3). This results in an influx of hydroxyl ions into the cell and thereby increases the intracellular pH and this effect is enhanced by using alkaline additive solutions. Examples of chloride-free alkaline additive solutions are AS-7 and PAGGGM. These additive solutions have been shown to preserve the redox metabolism and glycolysis activity during storage 40,45 . In addition, RBCs stored in AS-7 showed a higher post transfusion recovery than AS-5 stored RBCs 45 . PAGGGM stored RBCs, have not been tested in vivo yet. Figure 3. Mechanism of action of chloride-free alkaline additive solutions.