Incorporation of adenosine into ATP: formation of compartmentalized ATP

The incorporation of [3H]adenosine, [3H]adenine, and [3H]hypoxanthine into adenine nucleotides of nude (athymic) mouse liver and human hepatoma grown subcutaneously in nude mice was studied. 3H and 32P radioactive labeling in vivo of acid-soluble nucleotides followed by chromatographic procedures indicated that, in contrast to [3H]adenine and [3H]hypoxanthine, [3H]adenosine is preferentially incorporated into ATP in comparison with its incorporation into AMP and ADP. This phenomenon, as well as complementing the recently reported 3-fold increase in total cellular ATP upon treatmen- with 0.5-1.0 mM concentrations of adenosine, indicates the formation from adenosine of compartmentalized ATP that is not produced from either adenine or hypoxanthine. The observed effect is of larger magnitude in the growth-arrested normal liver than in the actively growing tumor.