IGF-I increases the recruitment of GLUT4 and GLUT3 glucose transporters on cell surface in hyperthyroidism

ObjectiveIn hyperthyroidism, tissue glucose disposal is increased to adapt to high energy demand. Our aim was to examine the regulation of glucose transporter (GLUT) isoforms by IGF-I in monocytes from patients with hyperthyroidism.Design and methodsBlood (20 ml) was drawn from 21 healthy and 10 hyperthyroid subjects. The abundance of GLUT isoforms on the monocyte plasma membrane was determined in the absence and presence of IGF-I (0.07, 0.14, and 0.7 nM) using flow cytometry. Anti-CD14-phycoerythrin monocional antibody was used for monocyte gating. GLUT isoforms were determined after staining the cells with specific antisera to GLUT3 and GLUT4.ResultsIn monocytes from the euthyroid subjects, IGF-I increased the abundance of GLUT3 and GLUT4 on the monocyte surface by 25 and 21% respectively (P