Pyrimidines oxygen uptake

The most common damage to pyrimidines is the formation of thymine glycol (Tg), which results from attack by a hydroxyl radical to yield a 5-hydroxy-6-yl radical. In the absence of oxygen, loss of an electron followed by uptake of water and loss of a proton generates thymine glycol. In the presence of oxygen, uptake of oxygen at position 6 first... 

The duration of coronary dilatation by adenosine is controlled in part by the active adenosine deaminase of the heart, and certain clinically useful vasodilators are believed to act through inhibition of adenosine deamination. Thus dipyridamole (Persantin), or 2,6-bis(diethanolamino)-4,8-dipiperidinopyrimido(5,4-d)pyrimidine is a smooth muscle relaxant used particularly as a coronary vasodilator it also increases cardiac oxygen consumption. It decreases nucleotide breakdown, causes an accumulation of adenosine in hypoxic heart muscle, and increases blood adenosine concentrations by decreasing its uptake by erythrocytes. Papaverine is also reported to decrease adenosine uptake by erythrocytes, and inhibition of adenosine deamination by ouabain has also been reported. 

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