Accumulation of Acetyl Groups Following Cycling: A 1H-MR Spectroscopy Study

L. J. White; R. A. Robergs; W. L. Sibbitt; C. M. Gasparovic; H. Petropoulos; W. M. Brooks

doi:10.1055/s-2005-837572

International Journal of Sports Medicine, Table of Contents

Int J Sports Med 2006; 27(2): 100-104
DOI: 10.1055/s-2005-837572

Physiology & Biochemistry

Accumulation of Acetyl Groups Following Cycling: A ¹H-MR Spectroscopy Study

L. J. White¹ ^, ³ , R. A. Robergs³ , W. L. Sibbitt² ^, ⁴ Jr. , C. M. Gasparovic² ^, ⁵ , H. Petropoulos² , W. M. Brooks⁶

¹Department of Applied Physiology and Kinesiology, Applied Human Physiology Laboratory, University of Florida, Gainesville, FL, USA
²Mind Imaging Center, University of New Mexico, Albuquerque, NM, USA
³Department of Human Performance Laboratory, University of New Mexico, Albuquerque, NM, USA
⁴Department of Internal Medicine, University of New Mexico, Albuquerque, NM, USA
⁵Department of Neurosciences, University of New Mexico, Albuquerque, NM, USA
⁶Hoglund Brain Imaging Center, University of Kansas Medical Center, School of Medicine, Kansas City, KS, USA

Abstract

Using in vivo proton magnetic resonance spectroscopy (¹H-MRS), a new peak resonating at 2.13 ppm post-exercise has been attributed in the literature to the acetyl groups of acetylcarnitine. Since this peak is inconsistently generated by various submaximal exercise regimens, this study aimed at (a) verification of the previous chemical assignment, (b) determination of exercise conditions necessary for its induction, and (c) documentation of the recovery kinetics through 60 minutes following exercise. Ten healthy males (31 ± 4 yr) cycled continuously for 45 minutes with intensity alternating between 50 % (3 min) and 110 % (2 min) of ventilatory threshold (VT). ¹H-MR spectra were acquired from the vastus lateralis before and for 60 minutes following exercise. The peak at 2.13 ppm was not quantifiable at rest in any subject. However, it was present in all subjects following intense exercise (p < 0.0001), and expressed the chemical characteristics of an acetyl-containing compound. The estimated concentration, accumulation with high-intensity exercise, the presence as a single peak at 2.13 ppm, and the chemical shift were all consistent with the chemical and biophysical characteristics of acetyl groups associated with acetylcarnitine. This study provides further evidence that acetyl groups are robustly generated by intense exercise, and that the accumulation of acetyl groups in healthy subjects is dependent on the degree of exercise intensity. ¹H-MRS may be used for the noninvasive study of muscle metabolism during exercise and recovery and may have special applications for studying the generation and transport of acetyl compounds, including acetylcarnitine.

Key words

Acetylcarnitine - magnetic resonance spectroscopy - exercise and muscle metabolism

Full Text

References

1 Boesch C, Slotboom J, Hoppeler H, Kreis R. In vivo determination of intra-myocellular lipids in human muscle by means of localized 1 H - MR-spectroscopy. Magn Reson Med. 1997; 37 484-493
2 Boesch C, Kreis R. Dipolar coupling and ordering effects observed in magnetic resonance spectra of skeletal muscle. NMR Biomed. 2001; 14 140-148
3 Caiozzo V J, Davis J A, Ellis J F, Azus J L, Vandagriff R, Prietto C A, McMaster W C. A comparison of gas exchange indices used to detect the anaerobic threshold. J Appl Physiol. 1982; 53 1184-1189
4 Carlin J I, Harris R C, Cederblad G, Constantin-Teodosiu D, Snow D H, Hultman E. Association between muscle acetyl-CoA and acetylcarnitine levels in the exercising horse. J Appl Physiol. 1990; 69 42-45
5 Constantin-Teodosiu D, Carlin J I, Cederblad G, Harris R C, Hultman E. Acetyl group accumulation and pyruvate dehydrogenase activity in human muscle during incremental exercise. Acta Physiol Scand. 1991; 143 367-372
6 Efron B, Tibshirani R J. An Introduction to the Bootstrap. New York; Chapman & Hall 1993
7 Evanochko W T, Pohost G M. Structural studies of NMR detected lipids in myocardial ischemia. NMR Biomed. 1994; 7 269-277
8 Haseler L, Robergs R A. Acute exericse induced changes in localized proton MR spectra of human skeletal muscle. 2nd Int Soc Mag Reson Med. 1994; 1 161
9 Kimber N EHG, Spriet L L, Dyck D J. Skeletal muscle fat and carbohydrate metabolism during recovery from glycogen-depleting exercise in humans. J Physiol. 2003; 548 919-927
10 Kreis R, Jung B, Rotman S, Slotboom J, Boesch C. Non-invasive observation of acetyl-group buffering by 1 H - MR spectroscopy in exercising human muscle. NMR Biomed. 1999; 12 471-476
11 Kreis R, Kamber M, Koster M, Felblinger J, Slotboom J, Hoppeler H, Boesch C. Creatine supplementation-part II: in vivo magnetic resonance spectroscopy. Med Sci Sports Exerc. 1999; 31 1770-1777
12 Lehninger Al N D, Cox M M. Principles of Biochemistry. New York; NY Worth Publishers Inc 1993
13 Sahlin K, Katz A, Broberg S. Tricarboxylic acid cycle intermediates in human muscle during prolonged exercise. Am J Physiol. 1990; 259 C834-841
14 van Loon L J, Greenhaff P L, Constantin-Teodosiu D, Saris W H, Wagenmakers A J. The effects of increasing exercise intensity on muscle fuel utilization in humans. J Physiol. 2001; 536 295-304
15 Watt M J, Heigenhauser G J, Dyck D J, Spriet L L. Intramuscular triacylglycerol, glycogen and acetyl group metabolism during 4 h of moderate exercise in man. J Physiol. 2002; 541 969-978
16 White L J, Robergs R A, Sibbitt Jr W L, Ferguson M A, McCoy S, Brooks W M. Effects of intermittent cycle exercise on intramyocellular lipid use and recovery. Lipids. 2003; 38 9-13

Ph.D. Lesley J. White

Department of Applied Physiology and Kinesiology
University of Florida

PO Box 118206

Gainesville, FL 32611-8206

Phone: + 3523929575 ext. 1338

Fax: + 35 23 92 03 16

Email: lwhite@hhp.ufl.edu