Toxicity of high dimethyl sulfoxide concentrations in rat heart freezing

Summary When hearts from rats were frozen with 15% dimethyl sulfoxide (DMSO) to −20°C and thawed, 80% resumed mechanical activity when the DMSO was washed out. Hearts treated similarly, except that the DMSO was 30%, failed to recover in all cases 8 except one. Hearts treated with 30% DMSO did not freeze. None of the hearts from animals pretreated for 4 days before the experiment with 2.0 mg per day of cortisone acetate and then cooled to −20°C with 30% DMSO resumed mechanical activity after warming. However, the cortisone did reduce edema formation in the hearts to 17% of that formed in hearts from untreated rats. The results demonstrate that 30% DMSO is toxic in rat heart preparations, in contrast to previous reports of the lack of toxicity of similar concentrations in other tissues.