Effect of cross-reinnervation on the expression of glut-4 and glut
-1 in slow and fast rat muscles.
J[grave]uhannsson, E., O. Wrhaug, and A. Bonen.
The Norwegian University of Sport and Physical Education, P.O. Box
40, Kringsj[circumflex]i 0807, Oslo, Norway, Department of Anatomy,
Institute of Basic Medical Sciences, University of Oslo, P.O Box
1105, Blindern 0317, Oslo, Norway, Department of Kinesiology,
University of Waterloo, Waterloo, Ontario, N2L 3G1 Canada
APStracts 3:0037R, 1996.
We determined whether the twitch-velocity phenotype or the metabolic
phenotype of a muscle influences the content of GLUT-4 and GLUT-1
proteins. The soleus (SOL) and extensor digitorum longus (EDL)
muscles were cross reinnervated (X-SOL, X-EDL). After three months
the X-EDL had become enriched in slow-twitch oxidative (SO) fibers
(70.5% SO) compared to its control (3.8 % SO), whereas the X-SOL
became enriched in fast-twitch oxidative-glycolytic (FOG) fibers
(78.6% FOG) compared to its control (10% FOG). Thus, the twitch
phenotype of the cross innervated SOL shifted to fast twitch muscle,
whereas cross-innervation EDL shifted to a slow-twitch muscle. In the
X-EDL the oxidative nature of the X-EDL was increased to 97%
oxidative fibers compared to 43% oxidative fibers in the N-EDL. In
the SOL the oxidative nature of the X-SOL was retained at 100%. GLUT
-4 content was increased 1.6 fold in the X-EDL (P<0.05) but was
not changed in the X-SOL (P>0.05). GLUT-1 content was increased
4-fold in X-EDL, but was not altered in the X-SOL. We conclude that
GLUT-4 and GLUT-1 content in muscle is related to the oxidative
phenotype of the muscle rather than the twitch-velocity phenotype.
Received 10 April 1995; accepted in final form 23 January 1996.
APS Manuscript Number R234-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96