Generation of inorganic pyrophosphate from extracellular adenosine triphosphate by human serum and plasma
Park, W.; Masuda, I.; Cardenal-Escarcena, A.; Palmer, D.W.; McCarty, D.J.
Journal of Rheumatology 23(7): 1233-1236
1996
ISSN/ISBN: 0315-162X PMID: 8823698 Document Number: 456624
Objective: To quantify inorganic pyrophosphate (PP-i) production from extracellular adenosine triphosphate (ATP) by human serum or plasma. Methods: Serial measurements of ATP hydrolysis (t-1/2) were performed by the luciferase method from a starting concentration of 1 mu-M in serum or platelet-poor plasma incubated under physiologic conditions. ATP was then pumped into another sample of each specimen using the rate constant derived from the ATP t-1/2 of that specimen. Trace (32P) gamma ATP was added at the start of the infusion; conversion to (32P) inorganic orthophosphate (Pi) and to (32P) PP-i was determined by precipitation of P-i as reduced phosphomolybdate before and after treatment with yeast pyrophosphatase. Results: ATP was hydrolyzed by all serum and plasma specimens; the rate of hydrolysis in serum and plasma from the same blood sample was nearly identical. PP-i was the major product, averaging 71%. Conclusion: PP-i is the major product of ATP catabolism in serum and platelet-poor plasma.