In this study the effect of ribose on heart function and infarct size after permanent coronary artery occlusion was analyzed. Methods: Ribose was i.v. infused in 12 weeks old female Sprague-Dawley rats (100 mg/(kg x h)) beginning the day before surgery (MI+R, n=12). Myocardial infarction (MI) was induced in by ligation of left coronary artery. NaCl or untreated infarct rats (MI-CTRL, n=12) as well as sham-operated animals served as controls (sham, n=18). Six hours after MI left ventricular (LV) function was measured with Millar-tip catheters, and the hearts were analyzed by EvansBlue/TTC staining. Results: LVSP decreased to 86±3 mmHg in MI-CTRL compared to 118±4 mmHg in sham, but was restored to 109±6 mmHg in MI+R 6 h after MI. Also, LV dP/dtmax (4.385±248, 6.319±369 and 5.994±459 mmHg/s in MI-CTRL, sham and MI+R, respectively) as well as LV dP/dtmin (-3.378±228, -6.129±410 and -5.050±424 mmHg/s) improved by ribose treatment. The infarct size 6 h after MI was reduced from 35±4% of the area at risk in MI-CTRL to 17±4% in ribose treated rats, despite a comparable area at risk in both groups (57±5% vs 62±6% of LV). Conclusion: LV function significantly improved by ribose treatment 6 h after MI. This seems to be based on slowing down the velocity of the necrotic wave front across the LV wall after MI resulting in smaller infarcts.