Effect of high ffa on glycogenolysis in oxidative rat hindlimb
muscles during twitch stimulation.
Dyck, David J., Sandra J. Peters, Paula S. Wendling, and Lawrence L.
Spriet.
School of Human Biology, University of Guelph, Guelph, Ontario,
CANADA N1G 2W1
APStracts 2:0291R, 1995.
The effect of elevated free fatty acids (FFA) on carbohydrate (CHO)
utilization in the oxidative muscles of the isolated rat hindlimb was
determined using twitch contraction paradigms evoking a wide range of
O2 uptakes and glycogenolysis. The hindlimb was perfused with either
0 or 1.8 mM FFA for 10 min at rest, and 20 min of stimulation at 0.4,
0.7, 1, 2, 3, or 4 Hz. Soleus (SOL), plantaris (PL) and red
gastrocnemius (RG) were sampled following rest perfusion or stimu
lation. FFA had little effect on glycogenolysis during stimulation,
although glycogen sparing occurred with one of the lesser intensity
protocols in each muscle (SOL, 0.4 Hz; RG, 0.7 Hz; PL, 1 Hz). Muscle
citrate and acetyl-CoA were elevated in SOL during several
stimulation protocols with high FFA, but this effect was inconsistent
in PL and RG. The sparing of glycogen, when it did occur, was
generally unrelated to increases in either citrate or acetyl-CoA
content. Furthermore, protocols in which citrate or acetyl-CoA were
elevated in the presence of elevated FFA did not demonstrate glycogen
sparing. Hindlimb lactate efflux at rest was reduced with FFA, but
unaffected during stimulation. Glucose uptake was unaffected by FFA
at rest and during all stimulation protocols, except 3 Hz. The
present study does not support the classically pro posed roles of
citrate and acetyl-CoA in the FFA-induced down-regulation of CHO
utilization in electrically stimulated rat skeletal muscle.
Received 4 May 1995; accepted in final form 19 October 1995.
APS Manuscript Number R268-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 November 95