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, alterations 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 transporters in normal and denervated diaphragm by immunohistochemistry method with specific Gluts antibodies. The results showed Glut-4 immunoreactivity in both 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. However, Glut-4 staining was stronger than Glut-1 staining in control diaphragm. In denervated hemidiaphragm, the Glut-4 immunolabelling decreased and Glut-1 increased. These data indicated that (1) Glut-4 and Glut-1 transporters were observed in diaphragm; and (2) there were alterations in the expression of both glucose transporters after denervation. These alterations in Glut isoforms after denervation may be associated with the removal of innervation itself, and/or may partly result from passive stretch imposed by inspiratory activation of the contralateral side. (C) 2000 Harcourt Publishers Ltd.