lactobionate-based improvement on University of Wisconsin-lactobionate solution; extracellular-type cardioplegic solution tested for improved myocardial preservation; contains sodium lactobionate, adenine, and a nitroxide radical: 4-hydroxy-2,2,6,6-tetramethylpiperidine-n-oxyl (TEMPOL); the lactobionate complexes Fe2+ and the nitroxide complexes Fe3+