Functional differences in lipid metabolism in resting skeletal muscle of various fiber types. Dyck, D. J., S. J. Peters, J. Glatz, J. Gorski, H. Keizer, B. Kiens, S. Liu, E. A. Richter, L. L. Spriet, G. J. Van Der Vusse, and A. Bonen. Department of Kinesiology, University of Waterloo, Ontario, Canada N2L 3G1, Department of Human Biology and Nutritional Sciences, University of Guelph, Ontario, Canada, N1G 2W1, The Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, DK-2100, Copenhagen, Denmark, Medical Academy of Bialystok, Dept. of Physiology, 15-230 Bialystok, Poland, Department of Motion Sciences, Department of Physiology, Cardiovascular Research Institute Maastricht, University of Limburg, 6200 MD Maastricht, The Netherlands.
APStracts 3:0226E, 1996.
Intramuscular lipid pool turnover (triacylglycerols (TG), phospholipids (PL), mono- and diacylglycerols (MG, DG)), and the oxidation of endogenous and exogenous lipids were determined with pulse-chase studies in incubated muscles of varied oxidative potential (soleus strips (SOL) > epitrochlearis (EPI) > flexor digitorum brevis (FDB)). Incorporation of palmitate into TG and PL pools, and its oxidation were linearly related to time and exogenous palmitate concentration in all muscles. Total palmitate incorporation (deposition and oxidation) was greatest in SOL. However, palmitate incorporation into TG was similar in all muscles when expressed as a percent of the total incorporation. In contrast, palmitate incorporation into PL was greatest in the least oxidative muscle. Palmitate oxidation, incorporation into TG, and citrate synthase activity were all strongly correlated with muscle cytosolic fatty acid binding protein (FABP) content (r=0.96, 1.0 and 0.98). During the chase, reducing exogenous palmitate from 1.0 mM to 0.5 or 0 mM resulted in a significant (30%) loss of 14C-palmitate from the TG pool in SOL, and a significant increase in 14CO2 production from endogenous stores. No significant loss of 14C-label from lipid pools occurred in the less oxidative muscles, suggesting a closely regulated interaction between energy provision from exogenous and endogenous lipid pools in oxidative muscle. Glucose oxidation increased significantly in all muscles in the absence of palmitate. The loss of 14C-label from TG in SOL during the chase without palmitate was not accompanied by a significant change in TG content. This suggests that during rest, there is a small subpool of TG with a relatively rapid turnover. 

Received 7 August 1996; accepted in final form 25 October 1996.
APS Manuscript Number E397-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996