Expression of Glut-4 and Glut-1 transporters in rat diaphragm muscle

Glucose transporters (Gluts) are a family of membrane proteins responsible for the transport of glucose across cellular membranes. Generally, alterati ons of Gluts expression in limb skeletal muscle have been reported. However , the changes of Glut isoforms in respiratory muscle which contracts with a duty cycle have rarely been studied. This study was performed to evaluate at the light microscopy level the expression of Glut-4 and Glut-1 transport ers in normal and denervated diaphragm by immunohistochemistry method with specific Gluts antibodies. The results showed Glut-4 immunoreactivity in bo th the cell periphery and the interior of myocytes. Glut-1 was also present in the cell border and in the interior of myocytes in control diaphragm. H owever, Glut-4 staining was stronger than Glut-1 staining in control diaphr agm. In denervated hemidiaphragm, the Glut-4 immunolabelling decreased and Glut-1 increased. These data indicated that (1) Glut-4 and Glut-1 transport ers were observed in diaphragm; and (2) there were alterations in the expre ssion of both glucose transporters after denervation. These alterations in Glut isoforms after denervation may be associated with the removal of inner vation itself, and/or may partly result from passive stretch imposed by ins piratory activation of the contralateral side. (C) 2000 Harcourt Publishers Ltd.