RT Journal Article SR Electronic T1 Detection of Cardiomyocyte Death in a Rat Model of Ischemia and Reperfusion Using 99mTc-Labeled Annexin V JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1536 OP 1541 VO 45 IS 9 A1 Taki, Junichi A1 Higuchi, Takahiro A1 Kawashima, Atsuhiro A1 Tait, Jonathan F. A1 Kinuya, Seigo A1 Muramori, Akira A1 Matsunari, Ichiro A1 Nakajima, Kenichi A1 Tonami, Norihisa A1 Strauss, H. William YR 2004 UL http://jnm.snmjournals.org/content/45/9/1536.abstract AB There is increasing evidence that cell death after myocardial ischemia and reperfusion may begin as apoptosis rather than necrosis. To determine the time course, location, and extent of this process, we studied groups of rats after a 20-min interval of coronary occlusion and reperfusion. Methods: After thoracotomy, the left coronary artery was occluded for 20 min. After release and before study, groups of animals were allowed to recover for various intervals: 0.5 h (n = 6), 1.5 h (n = 7), 6 h (n = 7), 1 d (n = 8), 3 d (n = 8), or 2 wk (n = 5). At the time of study, the rats were injected with 99mTc-annexin V (80–150 MBq). One hour later, to verify the area at risk, 201Tl (0.74 MBq) was injected intravenously just after the left coronary artery reocclusion and the rats were sacrificed 1 min later. Dual-tracer autoradiography was performed to assess 99mTc-annexin V uptake and the area at risk. Results: Extensive 99mTc-annexin V uptake was observed in the mid myocardium after 0.5–1.5 h of reperfusion. The area of annexin uptake had expanded in the subendocardial and subepicardial layers at 6 h after reperfusion and then gradually lessened over 3 d. At 0.5 and 1.5 h of reperfusion, 99mTc-annexin V uptake ratios were 7.36 ± 2.95 and 6.34 ± 2.24 (mean ± SD), respectively. The uptake ratios gradually decreased at 6 h, 1 d, 3 d, and 2 wk after reperfusion (4.65 ± 1.93, 3.27 ± 0.92 [P < 0.01 vs. 0.5 h], 1.84 ± 0.55 [P < 0.001 vs. 0.5 h, P < 0.005 vs. 1.5 h], and 1.65 ± 0.31 [P < 0.001 vs. 0.5 h, P < 0.005 vs. 1.5 h], respectively). Conclusion: These data indicate that annexin binding commences soon after ischemia and reperfusion in the mid myocardium within the area at risk and expands to include the subendocardial and subepicardial layers at 6 h after reperfusion, followed by gradual reduction of activity over 3 d.