Characterizing Adrenergic Regulation of Glucose Transporter 4-Mediated Glucose Uptake and Metabolism in the Heart.

Whereas adrenergic stimulation promotes cardiac function that demands more fuel and energy, how this receptor controls cardiac glucose metabolism is not defined. This study shows that the cardiac β adrenoreceptor (βAR) is required to increase glucose transporter 4 (GLUT4)-mediated glucose uptake in myocytes and glucose oxidation in working hearts via activating the cardiac βAR and promotes the G inhibitory-phosphoinositide 3-kinase-protein kinase B cascade to increase phosphorylation of TBC1D4 (aka AS160), a Rab guanosine triphosphatase-activating protein, which is a key enzyme to mobilize GLUT4. Furthermore, deleting G-protein receptor kinase phosphorylation sites of βAR blocked adrenergic stimulation of GLUT4-mediated glucose uptake in myocytes and hearts. This study defines a molecular pathway that controls cardiac GLUT4-mediated glucose uptake and metabolism under adrenergic stimulation.