Figure 2.

³¹P nuclear magnetic resonance (NMR) spectroscopy and magnetization transfer protocols.

A, Two groups of isolated rat hearts were used to simultaneously measure left ventricular contractile function and high-energy phosphates by ³¹P NMR spectroscopy in a Langendorff heart preparation: (1) perfused with increasing concentrations of dobutamine (60, 120, and 240 nmol/L for 20 min each, n=11) and (2) perfused with increasing concentrations of TA1 (15, 30, and 60 nmol/L for 20 min each, n=15). B, Two separate sets of isolated rat hearts were used to measure contractile function, ATP synthesis, and high-energy phosphate flux by ³¹P NMR magnetization transfer technique in a Langendorff heart preparation. Given that 60 nmol/L TA1 and 120 nmol/L dobutamine increased the rate-pressure product to the similar extent in ³¹P NMR spectroscopy experiments (as per A), for magnetization transfer experiments, the hearts were (1) perfused with 120 nmol/L dobutamine (n=10) and (2) perfused with 60 nmol/L TA1 (n=9). FA indicates fatty acids; and KH buffer, Krebs-Henseleit buffer. Created with BioRender.com.