Journal of Applied Physiology, Vol 49, Issue 5 851-855, Copyright © 1980 by American Physiological Society

ARTICLES

Uptake of chylomicron triglycerides by contracting skeletal muscle in rats

B. G. Mackie, G. A. Dudley, H. Kaciuba-Uscilko and R. L. Terjung

The influence of muscle stimulation (3 Hz) on the uptake of exogenously administered chylomicron 14C-labeled triglycerides (14C-TG) in the three different muscle fiber types was evaluated in fed and fasted pentobarbital-anesthetized rats. The fractional uptake of 14C-TG in the nonstimulated muscles was lowest in the fast-twitch white, intermediate in the fast-twitch red, and highest in the slow-twitch red muscle fiber section. Fasting doubled the uptake in both high-oxidative red fibers. These 14C-TG uptakes were directly proportional (r = 0.993) to their respective activities of lipoprotein lipase in these fiber types of fed and fasted animals reported by others. Muscle stimulation caused a significant increase in the fractional 14C-TG uptake in all of the fiber types. Although the TG uptake could account for only a small fraction of the total energy needs of the working muscle, it could contribute to the turnover of endogenous TG, especially in the slow-twitch red fibers. Further, the estimated TG uptake rate is sufficient to replace endogenous TG loss with an overnight rest following exercise. These results suggest that plasma TG could play an important role in lipid metabolism, especially in the high-oxidative slow and fast muscle fiber types.

This article has been cited by other articles:

				L. Magnoni, E. Vaillancourt, and J.-M. Weber High resting triacylglycerol turnover of rainbow trout exceeds the energy requirements of endurance swimming Am J Physiol Regulatory Integrative Comp Physiol, July 1, 2008; 295(1): R309 - R315. [Abstract] [Full Text] [PDF]

				T. W. Zderic and M. T. Hamilton Physical inactivity amplifies the sensitivity of skeletal muscle to the lipid-induced downregulation of lipoprotein lipase activity J Appl Physiol, January 1, 2006; 100(1): 249 - 257. [Abstract] [Full Text] [PDF]

				B. Mittendorfer, D. A. Fields, and S. Klein Excess body fat in men decreases plasma fatty acid availability and oxidation during endurance exercise Am J Physiol Endocrinol Metab, March 1, 2004; 286(3): E354 - E362. [Abstract] [Full Text]

				L. Bey and M. T Hamilton Suppression of skeletal muscle lipoprotein lipase activity during physical inactivity: a molecular reason to maintain daily low-intensity activity J. Physiol., September 1, 2003; 551(2): 673 - 682. [Abstract] [Full Text] [PDF]

				B. Mittendorfer, J. F. Horowitz, and S. Klein Effect of gender on lipid kinetics during endurance exercise of moderate intensity in untrained subjects Am J Physiol Endocrinol Metab, July 1, 2002; 283(1): E58 - E65. [Abstract] [Full Text] [PDF]

				E. Zernicka, E. Smol, J. Langfort, and M. Gorecka Time course of changes in lipoprotein lipase activity in rat skeletal muscles during denervation-reinnervation J Appl Physiol, February 1, 2002; 92(2): 535 - 540. [Abstract] [Full Text] [PDF]

				L. Bey, E. Areiqat, A. Sano, and M. T. Hamilton Reduced lipoprotein lipase activity in postural skeletal muscle during aging J Appl Physiol, August 1, 2001; 91(2): 687 - 692. [Abstract] [Full Text] [PDF]

				E. Smol, E. Zernicka, D. Czarnowski, and J. Langfort Lipoprotein lipase activity in skeletal muscles of the rat: effects of denervation and tenotomy J Appl Physiol, March 1, 2001; 90(3): 954 - 960. [Abstract] [Full Text] [PDF]

				J. F Horowitz and S. Klein Lipid metabolism during endurance exercise Am. J. Clinical Nutrition, August 1, 2000; 72(2): 558S - 563. [Abstract] [Full Text] [PDF]

				N. Abumrad, C. Harmon, and A. Ibrahimi Membrane transport of long-chain fatty acids: evidence for a facilitated process J. Lipid Res., December 1, 1998; 39(12): 2309 - 2318. [Abstract] [Full Text]