Trytl radical

The tissue slices were maintained at physiological conditions in the bioreactor in circulating media at 37°C with 95% air/5% CO₂ via a gas exchanger. All bioreactor experiments were conducted using a 500 MHz Varian Inova (Agilent Technologies, Palo Alto, California) with a 5-mm, triple-tune, direct-detect broadband probe. For the HP ¹³C pyruvate studies, 7.5 μL of 14.2 M [1-¹³C]pyruvate, mixed with 15 mM of the trytl radical (GE Health, Menlo Park, California) and 2.5 mM of gadolinium chelate, was polarized on a Hypersense polarizer (Oxford Instruments, Oxford, UK), followed by dissolution in 5 mL of 50 mM phosphate buffer. Next, 750 μL of the resulting 16 mM of HP ¹³C pyruvate solution was injected over 90 seconds into the bioreactor containing the tissue slices. HP ¹³C MR data were dynamically acquired with a 30° flip angle, pulse repetition time of 3 seconds, and for a duration of 300 seconds. ³¹P spectra were acquired before and after each HP ¹³C study to assess tissue viability using a repetition time of 2 seconds, 2048 averages, and a 90° flip angle. The β-nucleoside triosephosphate (βNTP) peak was quantified using the electronic reference to access in vivo concentrations (ERETIC) method as described previously (26 (link)).