Metformin improves cardiac functional recovery after ischemia in rats

The biguanide, metformin, is widely used for the treatment of type 2 diabetes mellitus. In the recently published United Kingdom Prospective Diabetes Study (UKPDS), it was shown that the use of metformin was associated with a reduction of macrovascular complications compared to other blood glucose-lowering strategies. The present study was aimed at determining whether metformin has direct beneficial effects on the heart. We tested the effects of metformin on cardiac functional recovery after a mild ischemic incident (stunning) in our isolated, erythrocyte perfused, rat working-heart model. Three groups were tested: vehicle, 50 and 500 mumol/l metformin (total n=6). In diabetic rats, a concentration of 50 muM has been shown to reduce the blood glucose concentration. Slight metformin-induced increases in coronary blood flow during normoxia (pre-ischemically) and during reperfusion (post-ischemically) were observed and compared to vehicle (p < 0.05). Both metformin concentrations significantly reduced cardiac functional loss induced by the 12-min global ischemic incident compared with vehicle (3.4 +/- 1.0% and 3.5 +/- 0.6% loss during metformin versus 10.7 +/- 0.8% during vehicle, p < 0.001). This study clearly shows that metformin acutely improves cardiac function after a mild ischemic incident (stunning) in rats.