In vivo assessment of cardiac metabolism and function in the abdominal aortic banding model of compensated cardiac hypertrophy.
OBJECTIVE
Left ventricular hypertrophy is an adaptive response of the heart to chronic mechanical overload and can lead to functional deterioration and heart failure. Changes in cardiac energy metabolism are considered as key to the hypertrophic remodelling process. The concurrence of obesity and hypertrophy has been associated with contractile dysfunction, and this work therefore aimed to investigate the in vivo structural, functional, and metabolic remodelling that occurs in the hypertrophied heart in the setting of a high-fat, high-sucrose, Western diet (WD).


RESULTS
Following induction of cardiac hypertrophy through abdominal aortic banding, male Sprague Dawley rats were exposed to either a standard diet or a WD (containing 45% fat and 16% sucrose) for up to 14 weeks. Cardiac structural and functional characteristics were determined by CINE MRI, and in vivo metabolism was investigated using hyperpolarized (13)C-labelled pyruvate. Cardiac hypertrophy was observed at all time points, irrespective of dietary manipulation, with no evidence of cardiac dysfunction. Pyruvate dehydrogenase flux was unchanged in the hypertrophied animals at any time point, but increased incorporation of the (13)C label into lactate was observed by 9 weeks and maintained at 14 weeks, indicative of enhanced glycolysis.


CONCLUSIONS
Hypertrophied hearts revealed little evidence of a switch towards increased glucose oxidation but rather an uncoupling of glycolytic metabolism from glucose oxidation. This was maintained under conditions of dietary stress provided by a WD but, at this compensated phase of hypertrophy, did not result in any contractile dysfunction.
School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull HU6 7RX, UK.
Anne-Marie L
AM
Seymour
Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK.
Lucia
L
Giles
Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK.
Vicky
V
Ball
Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK.
Jack J
JJ
Miller
Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK.
Kieran
K
Clarke
Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK.
Carolyn A
CA
Carr
Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK damian.tyler@dpag.ox.ac.uk.
Damian J
DJ
Tyler
D000821:Animal Feed; D000818:Animals; D001012:Aorta, Abdominal / Q000378:metabolism; D006332:Cardiomegaly / Q000378:metabolism*; D004195:Disease Models, Animal; D004734:Energy Metabolism / Q000502:physiology*; D006333:Heart Failure / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction; D017207:Rats, Sprague-Dawley
13C magnetic resonance spectroscopy; Cardiac hypertrophy; Dynamic nuclear polarization; Metabolic remodelling; Pyruvate dehydrogenase