Experimental Study of the Molecular Mechnisms of Myocardial Ischemic Memory With ¹⁸F-FDG PET/CT Imaging

This study was aimed to explore whether the changes of mRNA and the existence and duration of ischemic ¹⁸F-FDG uptake correlate with the extent of myocardial ischemia in ischemia reperfusion canine model. The 20 minute (n= 4) and 40 minute (n= 4) coronary artery occlusion followed by 24 h of openartery reperfusion in canine model were performed. All dogs underwent fasting (>12 h) dynamic ¹⁸F-FDG PET/CT and ⁹⁹Tc^m-MIBI SPECT imaging at baseline, 1 h and 24 h after reperfusion. When all imaging were completed, myocardial samples from the ischemic and nonischemic region were obtained, and the mRNA expression of glucose transporter-1 (GLUT-1), glucose transporter-4 (GLUT-4), and heart-fatty acid binding protein (H-FABP) were estimated by Real Time PCR. There was no difference in the ratio of hypoperfused region/nomoperfused region of ¹⁸F-FDG uptake between the 20-minute group and 40 minute group at baseline. When examined at 1 h, increased ¹⁸F-FDG uptake was observed in the 40 minute group. When estimated at 24 h, only the 40 minute group showed slightly higher ¹⁸F-FDG uptake than baseline, whereas no such difference was demonstrated in the 20minute group. Similar mRNA expression of GLUT-1, GLUT-4 and H-FABP were demonstrated in the nonischemic regions between the 2 groups, whereas increased expressions of GLUT-1 and GLUT-4, and decreased H-FABP mRNA were demonstrated in the ischemic regions. The changes of mRNA expression were more obvious in the 40 minute group than in the 20-minute group.The results showed that the existence and persistent period of ischemic ¹⁸F-FDGuptake (ischemic memory) was correlated with the extent of myocardial ischemia.