Adenosine receptor blockade enhances myocardial stunning without a sustained effect on fluorine-18-FDG uptake postreperfusion

The aim of this study was to determine whether adenosine receptor blockade before ischemia would enhance the degree of stunning and induce a sustained decrease in glucose uptake after reperfusion. Methods: Stunning was induced in 14 anesthetized swine by partially occluding the left anterior descending artery (LAD) for 20 min (> 80% flow reduction). Seven animals were pretreated with the nonspecific adenosine receptor blocker 8- phenyltheophylline (8-PT; 5 mg/kg), which decreased reactive hyperemia by an average of 38%. Myocardial glucose uptake was assessed 1 hr following reperfusion with PET and the glucose analog ¹⁸F-fluorodeoxyglucose (FDG). Results: Before ischemia, systolic shortening in the LAD region was 15% ± 6% in the control group and 16% ± 4% in the 8-PT group and in both groups was reduced to - 1% ± 2% during ischemia. After reperfusion, systolic shortening was 7% ± 3% in the control group and 2% ± 3% in the 8-PT group (p (0.05). Myocardial oxygen consumption before ischemia was 4.58 ± 3.03 μmol/min/g in the control group and 4.44 ± 1.83 μmol/min/g in the 8-PT group (ns) and neither were different after reperfusion. In the postischemic LAD region, myocardial glucose uptake was 0.18 ± 0.15 μmol/min/g in the control group and was similar to that of the 8-PT group (0.17 ± 0.08 μmol/min/g; ns). Conclusion: The nonspecific adenosine blocker 8-PT enhanced the degree of stunning when given before ischemia but did not induce a sustained effect on myocardial glucose uptake after reperfusion.