- Oral presentation
- Open Access
Myocardial fatty acid metabolism probed with hyperpolarized [1-13C]octanoate
© Yoshihara et al; licensee BioMed Central Ltd. 2015
- Published: 3 February 2015
- Octanoic Acid
- Myocardial Metabolism
- Myocardial Fatty Acid
- Metabolite Peak
The heart normally derives most of its energy from the oxidation of fatty acids. Myocardial metabolism can be monitored non-invasively by MRS using hyperpolarized (HP) 13C-labelled compounds; however, the vast majority of studies reported have used HP pyruvate and did not measure fatty acid catabolism. The myocardial metabolism of HP [1-13C]butyrate and [1-13C]acetate has been reported. The conversion of these short-chain fatty acids to acetyl-CoA does not involve successive rounds of beta-oxidation, as is the case for longer chain fatty acids, which are a more important source of cardiac energy. In this study we examined the applicability of hyperpolarized [1-13C]octanoate, a medium-chain fatty acid, as a probe of myocardial metabolism.
[1-13C]octanoic acid (4 M in DMSO, doped with stable trityl radical) was polarized by microwave irradiation (196.8 GHz) at 7 T & 1 K. After dissolution with superheated buffered D2O, ~0.04 mmol was infused via a femoral vein catheter into anesthetized Wistar rats in a 9.4 T horizontal bore scanner (Varian) and a series of single pulse (BIR-4, 300, TR ~3 s) gated 13C MRS acquisitions was performed with a surface coil positioned over the heart. To aid metabolite identification, HP [1-13C]acetate and/or 13C-urea were coinfused in several experiments.
This study demonstrates that in-vivo dissolution DNP metabolic experiments can be performed with 13C-labelled medium-chain fatty acids. Sufficient 13C polarization in octanoate survives circulation, tissue uptake, mitochondrial transport and conversion by beta-oxidation to acetyl-CoA to be detectible in the acetylcarnitine pool. HP octanoate can be used to directly probe the beta-oxidation of metabolically important fatty acids in the heart.
Work supported by the Swiss National Fund (grants #138146 & PPOOP1_133562).
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.