Effect of overexpressing glut-1 and glut-4 on insulin-and
contraction-stimulated glucose transport in muscle.
J[grave]uhannsson, Erlingur, Karl J. A. McCullagh, Xiao-Xia Han, Pasan
K. Fernando, Jorgen Jensen, Hans A. Dahl, and Arend Bonen.
The Norwegian University of Physical Education and Sport, P.O.Box
40 Kringsj[circumflex]i 0807 Oslo, Norway, Department of Anatomy,
Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo,
Norway, Department of Kinesiology, University of Waterloo, Waterloo,
Ontario, N2L 3G1 Canada.
APStracts 3:0107E, 1996.
To examine the effects of GLUT-1 on GLUT-4 dependent, insulin
-stimulated and contraction-stimulated 2-DG transport, we
overexpressed GLUT-1 in metabolically heterogeneous skeletal muscles
(red and white tibialis anterior (TA) and EDL), via 7 days of chronic
electrical stimulation. GLUT-1 was increased 1.6-16.4 fold
(P<0.05). Basal 2-deoxy-D-glucose (2-DG) transport was increased
1.7-3.0 fold (P<0.05), and was equal to (red TA and EDL;
P>0.05) or exceeded insulin-stimulated 2-DG transport by 50%
(white TA; P<0.05) in the control muscles. GLUT-4 was
concomitantly overexpressed (2.1-4.4 fold; P<0.05). Insulin
-stimulated 2-DG transport was increased 1.6-2.5 fold (P<0.05).
During muscle contractions 2-DG transport increased 9-12 fold
(P<0.05) in control muscles, but this was reduced by 25%
(P<0.05) in muscles overexpressing GLUT-1 and GLUT-4 (red TA and
EDL). In contrast, in the experimental white TA contraction
-stimulated 2-DG transport was increased 1.7 fold (P<0.05).
Therefore, overexpression of GLUT-1, when GLUT-4 is also
overexpressed, does not impair insulin-stimulated 2-DG transport,
although contraction-stimulated transport may be reduced in some
muscles.
Received 11 December 1995; accepted in final form 17 May 1996.
APS Manuscript Number E579-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 June 96