Uridine is a Marker of Viability in Myocardial Ischemia
To test the hypothesis that uridine may be a marker of viability in myocardial ischemia, myocardial uptake of uridine was compared to that of deoxyglucose, a conventional marker of viability, in experimental myocardial ischemia. Fifteen male Wistar rats had occlusion of the left coronary artery for 5, 10, or 60 min. Four h after reperfusion, 60 uCi of 3H uridine and 2 uCi of 14C deoxyglucose were administered intravenously and the animals were sacrificed 45 min later. Two min before sacrifice, 100 uCi of thallium-201 was injected intravenously as a marker of myocardial perfusion. After sacrifice, the heart was removed and the left ventricle was sliced in a breadloaf fashion into 20 segments. Thallium-201 radioactivity in each segment was determined with a gamma counter; 1 month later 3H and 14C radioactivity was determined with a beta counter. Then the target to normal ratio (T/N) of the myocardial segment was calculated. Triphenyl tetrazolium chloride (TTC) staining was examined in neighboring myocardial specimens.