The pigs were fed and received an oral glucose bolus (2 g/kg) 3.5 hours and 45 minutes before MRS, respectively. MRI and hyperpolarized [1-13C]pyruvate MRS were carried out at rest and under dobutamine-stress (10 µg/kg/min IV), which is used for mimicking exercise in the clinic36 (link). All examinations were carried out on a commercial 3 T MRI system (GE Healthcare). The [1-13C]pyruvate was hyperpolarized in a SPINLab polarizer (GE Healthcare)37 (link). At the start of pyruvate injection, 128 spectra were acquired. After post-processing38 (link), pyruvate to metabolite conversion was quantified using the area under the curve approach39 (link). Myocardial pH was estimated from the bicarbonate and lactate signals40 (link). Conventional MRI was analysed with segmentation and volume measures were normalised to body weight41 (link). The MRS stress data of one RVO animal and the stress data of one control animal were excluded due to equipment failure.
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