Fig. 5

Schematic summary of the direct stimulation of insulin to glucose oxidation in the heart. Insulin stimulates mitochondrial protein kinase B (Akt), protein kinase C-delta (PKC-δ) and glycogen synthase kinase-3 beta (GSK-3β). Mitochondrial Akt plays a prerequisite role in mediating the activation of pyruvate dehydrogenase (PDH) and stimulation of cardiac glucose oxidation. Mitochondrial PKC-δ acts as a negative feedback loop by opposing insulin action in the heart and limiting the activity of mitochondrial Akt. Mitochondrial GSK-3β is not involved in mediating the direct stimulation of insulin on cardiac glucose oxidation. PDP pyruvate dehydrogenase phosphatase, PDK pyruvate dehydrogenase kinase, MPC mitochondrial pyruvate carrier, GLUT1 insulin-independent glucose transporter, GLUT4 insulin-dependent glucose transporter