Media strips of hog carotid artery formed hypoxanthine and inosine during incubation under conditions of normoxia (95% O2, 5% CO2). During anoxia (95% N2, 5% CO2), hypoxanthine increased fivefold and inosine twofold. Stimulation with 124 mM K+ resulted in a twofold increase in hypoxanthine and a threefold increase in inosine. Concurrent with the increase in the concentrations of purine derivatives was a decrease in tissue ATP. Although significant amounts of adenosine were not detected in the medium of incubating artery strips, the following evidence suggests adenosine was formed and rapidly deaminated to inosine: 1) Exogenous adenosine added to the medium of incubating strips was rapidly deaminated to inosine. 2) Exogenous 5'-AMP concentration decreased, whereas adenosine and, subsequently, inosine levels increased during incubation of artery strips. The reaction was specific for 5'-AMP and the data suggest that AMP is dephosphorylated to adenosine. 3) The specific activity of exogenous [U-14C]adenosine added to the medium of incubated strips decreased after 15 min. It is concluded that adenosine is formed in isolated artery strips but is rapidly deaminated to inosine.
Adenosine Nucleotide Transporter
