Evaluating the protective role of ischaemic preconditioning in rat hearts using a stationary small-animal SPECT imager and 99mTc-glucarate.
OBJECTIVE
To examine the protective role of ischaemic preconditioning (IPC) in rat hearts using Tc-glucarate (GLA) and a stationary SPECT imager, FastSPECT.


METHODS
Twenty-four rats with 30 min myocardial ischaemia and 150 min reperfusion (IR) were studied as follows. The IPC group (n=6) underwent IPC (five cycles of 4 min ligation of the left coronary artery and reflow) before IR. The control group (n=7) was treated by IR without IPC. The SPT group (n=6) was subjected to IPC and an adenosine antagonist, 8-(p-sulfophenyl)-theophylline (SPT). The vehicle group (n=5) received IPC and SPT carrier vehicle. GLA was delivered intravenously 30 min post-reperfusion, and 2-h dynamic cardiac images were acquired by FastSPECT.


RESULTS
GLA showed 'hot-spot' accumulation in the ischaemic area-at-risk (IAR) and exhibited lower retention (% 5 min peak) in the IPC and vehicle groups (33.8+/-2.6 vs. 35.7+/-9.2, P>0.05) than in the control and SPT groups (63.1+/-5.3 vs. 54.8+/-4.8, P>0.05). The infarct size (% IAR) was larger in the control and SPT groups (48.2+/-6.3 vs. 41.7+/-6.3, P>0.05) than that in the IPC and vehicle groups (21.0+/-1.9 vs. 19.1+/-4.6, P>0.05). In terms of the ex-vivo IAR-to-normal radioactivity ratio, there was a statistical difference between the control and IPC groups (7.4+/-0.9 vs. 3.0+/-0.4), as well as the SPT and vehicle groups (7.4+/-1.0 vs. 3.4+/-0.5).


CONCLUSIONS
IPC offers cardioprotection and relates to the activation of adenosine receptors in rat hearts. FastSPECT GLA imaging is not only useful in detecting early ischaemia-reperfusion injury, but also valuable in evaluating cardioprotection.
Liu
Zhonglin
Z
Department of Radiology, University of Arizona, Tucson, Arizona 85724-5067, USA. zliu@radiology.arizona.edu
Barrett
Harrison H
HH
Stevenson
Gail D
GD
Furenlid
Lars R
LR
Pak
Koon Yan
KY
Woolfenden
James M
JM
D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D005937:Glucaric Acid / Q000031:analogs & derivatives*; D006801:Humans; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D015233:Models, Statistical; D009206:Myocardium / Q000473:pathology*; D015609:Organotechnetium Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D015427:Reperfusion Injury / Q000517:prevention & control; D012306:Risk; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D002316:Cardiotonic Agents; D015609:Organotechnetium Compounds; D018047:Receptors, Purinergic P1; C067171:technetium Tc 99m glucarate; D005937:Glucaric Acid