Skeletal muscle (1) H MRSI before and after prolonged exercise. II. visibility of free carnitine

Boss, Andreas; Kreis, Roland; Saillen, Pierre; Zehnder, Monica; Boesch, Chris; Vermathen, Peter (2012). Skeletal muscle (1) H MRSI before and after prolonged exercise. II. visibility of free carnitine. Magnetic resonance in medicine, 68(5), pp. 1368-75. New York, N.Y.: Wiley-Liss 10.1002/mrm.24167

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Carnitine (Car) buffers excess acetyl-CoA through the formation of acetylCar (AcCar). AcCar's acetyl group (AG-AcCar) gives rise to a peak at 2.13 ppm in ¹H MR spectra of skeletal muscle, whereas the trimethylammonium (TMA) groups of both, AcCar and Car, are thought to contribute to the TMA peak at 3.23 ppm. Surprisingly, in previous studies both resonances, AG-AcCar and TMA, increased after exercise. The aim of this study was to assess if the exercise-related TMA increase correlated with AcCar production. Magnetic resonance spectroscopic imaging (pulse repetition time/echo time = 1200/35 ms) was performed before and after prolonged exercise in the lower leg and thigh of eight runners and eight cyclists, respectively. TMA and AG-AcCar increased after exercise (P < 0.001). TMA's increase correlated with the AG-AcCar increase (R² = 0.73, P < 0.001, lower leg; R² = 0.28, P < 0.001, thigh). The correlation of ΔTMA with ΔAG-AcCar suggests that the TMA increase is due to AcCar formation. As total Car (Car + AcCar) remains unchanged with exercise, these findings suggest that the contribution of free Car to the TMA peak is limited and, therefore, is partly invisible in muscle ¹H MR spectra. This indicates that the biochemically relevant cytosolic content of free Car is considerably lower than the overall concentration determined by radioisotopic assays, a potentially important result with respect to regulation of substrate oxidation.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic, Interventional and Paediatric Radiology > DCR Magnetic Resonance Spectroscopy and Methodology (AMSM)
UniBE Contributor:	Boss, Andreas, Kreis, Roland, Boesch, Christoph Hans, Vermathen, Peter
ISSN:	0740-3194
Publisher:	Wiley-Liss
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:20
Last Modified:	02 Mar 2023 23:20
Publisher DOI:	10.1002/mrm.24167
PubMed ID:	22287218
Web of Science ID:	000310062300004
URI:	https://boris.unibe.ch/id/eprint/6513 (FactScience: 211492)