Possible Interaction: Adenosine and Guanosine

“Although high micromolar (10–30 μM) guanosine did not increase accumulation of extracellular adenosine generated from endogenous VSMC sources under basal conditions, the presence of guanosine markedly suppressed the rate at which exogenously added adenosine (in the micromolar range) was cleared.”

“Jackson et al. used pharmacological approaches to test whether guanosine might compete with adenosine for either the metabolic enzymes (adenosine deaminase, adenosine kinase, SAH) or the nucleoside reuptake transporters (CNTs and ENTs) that participate (directly or indirectly) in the regulation of extracellular adenosine homeostasis (1).”

“Extracellular adenosine levels 1 h after addition of adenosine (3 μmol/l) plus guanosine (30 μmol/l) were 1.173 ± 0.061 μmol/l, indicating slow disposition of extracellular adenosine.”

“Inosine base pairs as guanosine and A‐to‐I editing can therefore alter the structure and base pairing properties of the RNA molecule.”

“A sharp turn in the phosphodiester backbone occurs between the second guanosine and third adenosine.”

“ Adenosine inhibited the effects of guanosine , in part by competing for uptake.”

“Guanosine also inhibits Na(+)-dependent uridine uptake, although there is some residual transport activity (35% of the control values) that is resistant to high concentrations of guanosine but may be inhibited by low concentrations of adenosine.”

“Inosine, guanosine , 2'-deoxyadenosine, tubercidin, formycin B, and the pyrimidines uridine, thymidine, and cytidine (all 100 microM) inhibited transport of adenosine and inosine about 50-100%, while 3'-deoxyinosine showed weak inhibitory action.”

“Here we report that adenosine can activate HPV16 late gene expression in a dose- and time-dependent manner, but only in the presence of guanosine.”

“Linear relationships and high correlations were observed between the levels of two guanosine- and adenosine –guanosine-adducts in normal and tumor tissue.”

“Although extracellular ATP has no effect on intracellular nucleotide metabolism, its degradation product adenosine significantly inhibits purine biosynthesis de novo as well as the salvage of adenine, hypoxanthine, guanosine or thymidine in both B and T lymphocytes.”