Blood bank conditions and RBCs: the progressive loss of metabolic modulation

BACKGROUND: Human RBC metabolism is modulated by the cell oxygenation state . Among other mechanisms, competition of deoxyhemoglobin and some glycolyti c enzymes for the cytoplasmic domain of band 3 is probably involved in modu lation. This metabolic modulation is connected to variations in intracellul ar NADPH and ATP levels as a function of the oxygenation state of the cell, and, consequently, it should have physiologic relevance. The present study investigates the effect of storage on this metabolic modulation and its re lationship with the alteration of membrane protein composition. STUDY DESIGN AND METHODS: RBCs stored in CPD-saline-adenine-glucose-mannito l were assayed for glucose uptake and partition between glycolysis and the pentose phosphate pathway at high and low oxygen saturation by nuclear magn etic resonance spectroscopy after 1, 14, 21, 35, and 42 days of storage. Me mbrane protein composition was determined by SDS-PAGE on Days 1, 14, 35, an d 42. Metabolic values and 2,3 DPG concentration were also measured after r ejuvenation for 1 hour at 37 degrees C with pyruvate-inosine-phosphate-aden ine solution on Day 21. RESULTS: Metabolic differences between RBCs incubated at high and low oxyge n saturation decreased during storage, and, on Day 35, the two groups did n ot have significant differences (p = 0.111). SDS-PAGE showed that membrane protein composition was concurrently modified. The percentage of unmodified band 3 decreased during storage, principally between Days 14 and 35. In re juvenated RBCs, oxygen-dependent modulation was not restored. CONCLUSIONS: RBCs stored in CPD-saline-adenine-glucose-mannitol do show a p rogressive loss of oxygen-dependent metabolic modulation, which is not rest ored after rejuvenation and which seems partly related to modifications in membrane proteins, mainly band 3.