Depletion of dense granule nucleotides during storage of human platelets

The energy metabolism of human platelets was studied during storage of platelet concentrates. The platelets were prepared from buffy coats in PVC/DEHP bags and stored for 7 days at room temperature at a concentration of 1.0 x 10(9)/ml with horizontal agitation. The total amount of ATP and ADP decreased with 40% during this storage. This decrease correlated with the disc-to-sphere transformation associated with the loss of platelet viability. During storage, the ability to incorporate 3H-adenosine into metabolic ATP and ADP (45 min at 37 degrees C) decreased with 50%. Via measurement of the specific activity of actin-bound ADP and the amount of incorporated radioactivity into total ATP and ADP, we calculated the content of the metabolic and storage pools of ATP and ADP. The results indicate that the decrease in adenine nucleotide levels during storage was mainly caused by a depletion of ATP and ADP from the storage pool, whereas the metabolic pool remained nearly intact. After 7 days, the ATP:ADP ratio of the storage pool had decreased from 1.0 to 0.3, indicating hydrolysis of ATP. Diadenosine-triphosphate and diadenosine-tetraphosphate (present in the storage pool) decreased with only 30%, and the serotonin content remained nearly constant. Therefore, it is unlikely that the storage pool was completely secreted. Probably, the storage pool of nucleotides serves as an internal supply for maintaining the contents of the metabolic pool of ATP and ADP during storage of platelets.