Inosine attenuates glycolysis in erythrocytes via glucose transporter inhibition

BackgroundBlood glucose concentrations decrease after blood collection. We recently developed novel blood collection tubes containing inosine added to sodium fluoride (NaF; FI tubes), which effectively inhibits post-collection blood glucose decline. However, the underlying mechanism remains unclear. In this study, we examined the mechanism by which inosine inhibits blood glucose consumption by erythrocytes and assessed glucose transporter (GLUT) activity.MethodsATP levels were measured in erythrocytes treated with inosine, and metabolomic changes were analyzed using GC-MS. In addition, glucose uptake tests were performed.ResultsIn patients' blood samples, FI tubes suppressed the post-collection decline in blood glucose levels more effectively than conventional NaF tubes, regardless of baseline blood glucose levels. FI tubes attenuated the time-dependent decrease in ATP levels; however, similar to that in conventional NaF tubes, ATP levels in erythrocytes in FI tubes were nearly zero after 4 h. Metabolic analysis demonstrated a decrease in the levels of glucose and glycolytic metabolites, such as 2-phosphoglycerate and phosphoenolpyruvate, in inosine-treated erythrocytes. Glucose uptake assays revealed that inosine significantly inhibited glucose uptake, indicating suppression of GLUT activity.ConclusionsInosine inhibits glucose uptake in erythrocytes primarily via the suppression of GLUT activity. It also inhibits erythrocyte hemolysis by temporarily maintaining intracellular ATP levels.