Spatial and temporal change of C-14-methionine uptake in a rat model of acute ischemia and reperfusion

Objectives Cellular methionine uptake reflects not only protein synthesis but also amino acid transport and transmethylation. Relation between C-11-methionine uptake and angiogenesis has been suggested in cerebral infarction and gliomas. However, there are no reports of methionine uptake in experimental ischemic myocardium. Therefore, to investigate the serial change in the uptake of methionine after severe myocardial ischemia and reperfusion, C-14 methionine imaging was performed in a rat model of acute ischemia and reperfusion.

Methods The left coronary artery was occluded for 30-min followed by reperfusion for 1, 3, 7, 14, 28 days, 3 and 6 month and C-14 methionine (7.4MBq) was injected intravenously 20 min before sacrifice. 10min before sacrifice Tl-201 (14.8MBq) was injected, and to verify the area at risk, 1 min before sacrifice the coronary artery was reoccluded and Tc-99m-MIBI (150-180 MBq) was injected. Triple tracer autoradiography was performed to assess methionine and Tl uptake and area at risk (perfusion defect by Tc-99m-MIBI).

Results C-14 methionine and Tl uptake was reduced in the area at risk at 1 day after reperfusion. However, 3 days after reperfusion, increased methionine uptake was observed corresponding to reduced Tl uptake area. Methionine uptake peaked at 3-7 days after reperfusion followed by gradual decline of uptake until 6 month (uptake ratios at day 1, 3, 7, 14, 28, and 3 month were 0.71 ± 0.13, 2.03 ± 0.33, 1.91 ± 0.26, 1.47 ± 0.15, 1.26 ± 0.079, 1.15 ± 0.073, 1.06 ± 0.049 respectively).

Conclusions C-14 methionine accumulated to infracted area and the uptake seems to correspond to tissue remodeling