DOI: 10.2337/db07-1098
Acute Metformin Therapy Confers Cardioprotection Against Myocardial Infarction Via AMPK-eNOS Mediated Signaling
1Department of Medicine, Division of Cardiology and Objective: Clinical studies have reported that metformin reduces cardiovascular end points of type-2 diabetics by actions that cannot solely be attributed to glucose-lowering effects. The therapeutic effects of metformin have been reported to be mediated by its activation of AMP-activated protein kinase (AMPK), a metabolite sensing protein kinase whose activation following myocardial ischemia has been suggested to be an endogenous protective signaling mechanism. We investigated the potential cardioprotective effects of a single, low-dose metformin treatment (i.e. 286-fold less than the maximum anti-hyperglycemic dose) in a murine model of myocardial ischemia-reperfusion (I/R) injury. Research Design and Methods: Non-diabetic and diabetic (db/db) mice were subjected to transient myocardial ischemia for a period of 30 min followed by reperfusion. Metformin (125 µg/kg) or vehicle (saline) was administered either prior to ischemia or at the time of reperfusion. Results: Administration of metformin prior to ischemia or at reperfusion decreased myocardial injury in both non-diabetic and diabetic mice. Importantly, metformin did not alter blood glucose levels. During early reperfusion, treatment with metformin augmented I/R-induced AMPK activation and significantly increased endothelial nitric oxide (eNOS) phosphorylation at residue serine 1177. Conclusions: These findings provide important information that myocardial AMPK activation by metformin following I/R sets into motion events, including eNOS activation, which ultimately lead to cardioprotection.
Correspondence: dlefer{at}aecom.yu.edu
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