Glycogenesis and glyconeogenesis in human platelets

Platelet storage at 22°C; metabolic, morphologic, and functional studies

“…At this time, therefore, we are not able to suggest the nature of the "storage lesion." In all in vitro systems described to date (17,29), platelet glycogen is depleted as time passes. Karpatkin, Charmatz, and Langer (29) have also observed that glycogen levels fall more rapidly when platelets are concentrated; no explanation for this phenomenon is apparent.…”

“…In all in vitro systems described to date (17,29), platelet glycogen is depleted as time passes. Karpatkin, Charmatz, and Langer (29) have also observed that glycogen levels fall more rapidly when platelets are concentrated; no explanation for this phenomenon is apparent. The cell possesses the capacity to maintain ATP levels, to utilize extracellular glucose, and to increase glucose utilization dramatically when stimulated as shown by the incubations in the presence of NaCN.…”

New Aspects of Glycogen Metabolism

“…Recently, Karpatkin and Langer (770,771) have demonstrated that inactive phosphorylase species exist in platelets (both monomeric and dimeric) and that these can be activated by treatment with ATP-Mg2+. Deficiencies of phosphorylase kinase in liver (766) and liver tumor (767) associated with increased deposition of glycogen and low phosphorylase activity have been reported.…”