Clearance and maintenance of blood nucleotide levels with adenosine triphosphate-magnesium chloride injection.

ATP-MgCl2 has been found to be helpful in experimental animals after shock and ischemia with improvement in organ function and survival. The reasons for this pharmacologic action are unclear. To evaluate the clearance and circulation of ATP and its metabolites after intravenous injection, 20 rabbits received ATP-MgCl2 as a bolus injection or a continuous intravenous infusion. Arterial blood was withdrawn, and ATP and its metabolites were measured using a high-performance liquid chromatography (HPLC) technique with ultraviolet (UV) absorption. Forty seconds following a bolus injection, only 1% of the injected dose was present in arterial blood as ATP, and at 280 sec only inosine remained. With a 60 min continuous ATP-MgCl2 infusion, the inosine level peaked at 62.9% at 30 min and was 37.6% at 60 min, whereas ATP was 4.9% and AMP was 17.4% at 60 min. Thus a single dose of ATP-MgCl2 has a half-life of less than 40 sec as ATP. With a continuous infusion, although some ATP circulates, inosine and AMP are the major remaining nucleotides. Thus, the beneficial effects of ATP-MgCl2 may be through ATP itself with magnesium or with adenine nucleotide metabolites for recycling of the nucleotides, phosphorylation of cell membrane inositides, and/or its vasoactive effects.