Penetration of ATP into the Myocardium. ∗

Summary

When the isolated guinea pig heart is perfused with C¹⁴- and P³²-labeled ATP of known isotope ratio, ATP isolated from the myocardium shows an isotope ratio 100 times greater than the starting material. Inorganic P³² is liberated into the perfusion fluid along with C¹⁴-labeled dephosphorylation and deamination products of ATP. UTP, GTP, CTP and ITP are also dephosphorylated when perfused. The results indicate that the ATP molecule does not enter the myocardium as such, but first is degraded and later resynthesized intracellularly.