The Mechanism of Action of Adenine in Red Cell Preservation*

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Abstract
Adenine-Cl4 (0.6 umole per ml) was added to acid-citrate-dextrose-blood at the outset or after 2 weeks of refrigerated storage, and its effect on the concentration and specific radioactivity of purines and purine necleotides was determined throughout a 6-week storage period. With supplementation at the outset, the initial adenine concentration decreased rapidly at first, then more slowly, so that by 6 weeks, about one-half of the initial adenine remained. The adenine was incorporated into adenine nucleotides, resulting in net adenine nucleotide synthesis and values of adenosine triphosphate and of total adenine nucleotides that were about 12 and 25% higher, respectively, after 1 to 2 weeks of storage than at the outset. Thereafter, the total adenine nucleotide concentrations declined but more gradually than in the acid-citrate-dextrose controls. This slower decline could be accounted for by continued incorporation of adenine into nucleotide rather than by inhibition of nucleotide breakdown. Adenine supplementation after 2 weeks of storage was less effective in maintaining adenine nucleotide levels than was supplementation at the outset. The data support the following hypotheses 1) adenine is first incorporated into adenosine monophosphate by reacting, presumably, with 5-phos-phoribosyl-1-pyrophosphate, 2) inosine monophosphate is not a major intermediate in the conversion of adenosine monophosphate to hypoxan-thine, and 3) no adenine is formed in blood during refrigerated storage.