BOLD-MRI was performed at 3 Tesla (Signa Echo Speed; GE Medical Systems, Milwaukee, Wisconsin, USA). Anesthesia was maintained with inhaled isoflurane (1–2%) throughout the course of the scanning. Myocardial oxygenation was measured using 4–5 BOLD-MRI slices, prescribed along the heart short axis. Images were acquired during suspended respiration using Fast Gradient Echo sequence with repetition time/echo time/number of echoes/matrix size/ field of view/slice thickness/flip angle equal to 6.8 ms/ 1.6–4.8 ms/8/128 ×128/35/0.5 cm/30°. For data analysis, regions of interest were manually traced in the left ventricular wall myocardium on the 7-ms echo time image (Fig. 1a). Myocardial R2* values were estimated in each voxel by fitting the magnetic resonance (MR) signal intensity vs. echo times to a single exponential function and calculating the MR intensity decay rate, as previously shown [18 (link)].