Regulation of skeletal muscle metabolism in the lizard dipsosaurus
dorsalis by fructose-2,6-bisphosphate.
Scholnick, David A., and Todd T. Gleeson.
University of Colorado, Department of Environmental Population and
Organismic Biology, Boulder, Colorado 80309-0334
APStracts 3:0195R, 1996.
Changes in liver and skeletal muscle Fru-2,6-P2 concentrations were
compared during fasting, exercise, and recovery in the lizard
Dipsosaurus dorsalis and in outbred mice (Mus musculus). We present
the first correlative evidence that suggests that a decrease in the
content of Fru-2,6-P2 may mediate elevated gluconeogenesis in lizard
skeletal muscle. Contents of Fru-2,6-P2 in lizard gastrocnemius, red,
and white iliofibularis (IF), were significantly lower (as much as
55% in white IF) during recovery from exhaustive exercise than at
rest. Recovery from exhaustive exercise had no significant effect on
Fru-2,6-P2 concentrations in any mouse muscle examined. Fasting
significantly depressed lizard and mouse liver Fru-2,6-P2 contents
and decreased lizard red IF by over 84% from the fed condition.
Lizard red and white muscle fiber bundles incubated in 20 mM lactate
had significantly lower Fru-2,6-P2 (94% and 61% depression
respectively) than those incubated in 8.5 mM glucose. These results
are consistent with the hypothesis that Fru-2,6-P2 acts as a signal
for controlling gluconeogenesis in lizard skeletal muscle.
Received 13 September 1995; accepted in final form 10 May 1996.
APS Manuscript Number R569-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 June 96