(99m)Tc-Annexin-V uptake in a rat model of variable ischemic severity and reperfusion time.
BACKGROUND
To determine whether mild to moderate ischemia that is not severe enough to induce myocardial infarction will cause myocardial cell damage or apoptosis, the (99m)Tc-Annexin-V (Tc-A) uptake was studied in groups of rats with various intervals of coronary occlusion and reperfusion times.


RESULTS
After left coronary artery occlusion for 15 min (n=23), 10 min (n=23), or 5 min (n=12), Tc-A (80-150 MBq) was injected at 0.5, 1.5, 6, or 24 h after reperfusion. One hour later, to verify the area at risk, (201)Tl (0.74 MBq) was injected just after left coronary artery re-occlusion and the rats were killed 1 min later. Dual tracer autoradiography was performed to assess Tc-A uptake and area at risk. In all 5-min occlusion and reperfusion models, no significant Tc-A uptake was observed in the area at risk. Tc-A uptake ratios in the 15-min and 10-min ischemia models were 4.46+/-3.16 and 2.02+/-0.47 (p=0.078) at 0.5 h after reperfusion, 3.49+/-1.78 and 1.47+/-0.11 (p<0.05) at 1.5 h after reperfusion, 1.60+/-0.43 and 1.34+/-0.23 (p=0.24) at 6 h after reperfusion, 1.50+/-0.33 and 1.28+/-0.33 (p=0.099) at 24 h after reperfusion, respectively. With 15-min ischemia, in 3 of the 5 rats there were a few micro-foci of myocardial cell degeneration and cell infiltration in less than 1% of the ischemic area at 24 h after reperfusion. No significant histological change was observed in rats with 10-min or 5-min ischemia.


CONCLUSIONS
The data indicate that Tc-A binding depends on the severity of ischemia even without a significant amount of histological change or infarction.
Taki
Junichi
J
Department of Biotracer Medicine, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan. taki@med.kanazawa-u.ac.jp
Higuchi
Takahiro
T
Kawashima
Atsuhiro
A
Tait
Jonathan F
JF
Muramori
Akira
A
Matsunari
Ichiro
I
Nakajima
Kenichi
K
Vanderheyden
Jean-Luc
JL
Strauss
H William
HW
D000818:Animals; D017304:Annexin A5 / Q000493:pharmacokinetics*; D017209:Apoptosis; D001345:Autoradiography; D004195:Disease Models, Animal; D020287:In Situ Nick-End Labeling; D008297:Male; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics*; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000378:metabolism* / Q000473:pathology*; D012720:Severity of Illness Index; D013997:Time Factors
D017304:Annexin A5; D015609:Organotechnetium Compounds; C417036:technetium Tc 99m annexin V