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This Article Full Text Full Text (PDF) All Versions of this Article: 295/6/H2328    most recent 00091.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Yang, Z. Articles by French, B. A. PubMed PubMed Citation Articles by Yang, Z. Articles by French, B. A.

Timing of adenosine 2A receptor stimulation relative to reperfusion has differential effects on infarct size and cardiac function as assessed in mice by MRI

Departments of ¹Surgery, ²Biomedical Engineering, ³Medicine, and ⁴Radiology, University of Virginia, Charlottesville, Virginia

Submitted 30 January 2008 ; accepted in final form 8 October 2008

The activation of adenosine 2A receptors before reperfusion following coronary artery occlusion reduces infarct size and improves ejection fraction (EF). In this study, we examined the effects of delaying treatment with the adenosine 2A receptor agonist ATL146e (ATL) until 1 h postreperfusion. The infarct size and EF were serially assessed by gadolinium-diethylenetriaminepentaacetic acid-enhanced MRI in C57BL/6 mice at 1 and 24 h postreperfusion. The infarct size was also assessed by 2,3,5-triphenyltetrazolium chloride staining at 24 h. Mice were treated with ATL (10 µg/kg ip) either 2 min before reperfusion (early ATL) or 1 h postreperfusion (late ATL) following the 45-min coronary occlusion. The two methods used to assess infarct size at 24 h postreperfusion (MRI and 2,3,5-triphenyltetrazolium chloride) showed an excellent correlation (R = 0.96). The risk region, determined at 24 h postreperfusion, was comparable between the control and ATL-treated groups. The infarct size by MRI at 1 versus 24 h postreperfusion was 25 ± 1 vs. 26 ± 1% of left ventricular mass (means ± SE) in control mice, 16 ± 2 versus 17 ± 2% in early-ATL mice, and 24 ± 2 versus 25 ± 2% in late-ATL mice (intragroup, P = not significant; and intergroup, early ATL vs. control or late ATL, P < 0.05). EF was reduced in control mice but was largely preserved between 1 and 24 h in both early-ATL and late-ATL mice (P < 0.05). In conclusion, after coronary occlusion in mice, the extent of myocellular death due to ischemia-reperfusion injury is 95% complete within 1 h of reperfusion. The infarct size was significantly reduced by ATL when given just before reperfusion, but not 1 h postreperfusion. Either treatment window helped preserve the EF between 1 and 24 h postreperfusion.

magnetic resonance imaging; infarction; inflammatory activation; reperfusion injury