Preservation of erythrocytes using metabolic regulators and mutrients. V. Inosine and methylene blue.

Methylene blue and inosine have been shown to stimulate glycolytic metabolism in the erythrocytes, increasing the concentration of 2.3-diphosphoglycerate (2,3-DPG), which is necessary for hemoglobin function, by regulating oxidative metabolism and providing a five-carbon nutrient for glycolysis, respectively. However, a recent study suggested that the methylene blue effect was dependent on the presence of inosine. This study was designed to establish, if possible, the existence of a methylene blue effect and to confirm the usefulness of inosine. The optimal concentration of inosine for increasing 2,3-DPG synthesis in a CPD-adenine preservative is confirmed to be 10--15 mM. Concentrations of 2,3-DPG were maintained in the erythrocytes at normal or higher levels for 21 days of storage with 10 or 15 mM inosine, whether the methylene blue was present or not. However, when methylene blue was present, 2,3-DPG concentrations were significantly better maintained.