Myocardial reperfusion decreases glucose oxidation and uncouples glucose oxidation from glycolysis. Therapies that increase glucose oxidation lessen myocardial ischemia/reperfusion injury. However, the regulation of glucose uptake during reperfusion remains poorly understood. Here we found that glucose uptake was remarkably diminished in myocardium following reperfusion in Sprague-Dawley rats as detected by 18F-labeled and fluorescent-labeled glucose analogs, even though GLUT1 was upregulated by 3 folds and GLUT4 translocation remained unchanged compared with those of sham rats. The decreased glucose uptake was accompanied by suppressed glucose oxidation. Interestingly, stimulating glucose oxidation by inhibition of pyruvate dehydrogenase kinase 4 (PDK4), a rate-limiting enzyme for glucose oxidation, increased glucose uptake and alleviated ischemia/reperfusion injury. In vitro data in neonatal myocytes showed that PDK4 overexpression decreased glucose uptake, while its knockdown increased glucose uptake, suggesting a role of PDK4 in regulating glucose uptake. Moreover, inhibition of PDK4 increased myocardial glucose uptake with concomitant enhancement of cardiac insulin sensitivity following myocardial ischemia/reperfusion. These results showed that the suppressed glucose oxidation mediated by PDK4 contributes to the reduced glucose uptake in myocardium following reperfusion, and enhancement of glucose uptake exerts cardioprotection. The findings suggest that stimulating glucose oxidation via PDK4 could be an efficient approach to improve recovery from myocardial ischemia/reperfusion injury.
- glucose uptake
- glucose oxidation
- myocardial ischemia/reperfusion injury
- myocardial insulin sensitivity
- Copyright © 2017, American Journal of Physiology-Endocrinology and Metabolism