31P NMR studies on rejuvenation of outdated red blood cells: complete regeneration of ATP is accompanied by partial Mg-ATP recomplexation.

We used 31P Nuclear Magnetic Resonance (NMR) spectroscopy to investigate whether regeneration of ATP in outdated human blood is accompanied by Mg-ATP recomplexation. We found that the loss of 'total ATP' (i.e. the sum of ATP4- + MG-ATP2-) which occurs during blood storage is completely reversible by treatment of RBC with precursors for purine nucleotide salvage. The magnesium-ATP complex, however, is only partially (70%) recovered due to a continuous decline of cytosolic free Mg2+ with increasing RBC age. Total RBC magnesium, as measured by flame absorption spectroscopy, did not show any significant change under these conditions.