DETERIORATION OF COLD-STORED TISSUE SPECIMENS DUE TO LIPID-PEROXIDATION - MODULATION BY ANTIOXIDANTS AT HIGH SUBZERO TEMPERATURES

It is often necessary to store tissue specimens in subzero conditions for assay in batches. During storage at -20 °C we found that sufficient lipid peroxidation occurred in rat liver homogenates in phosphate-buffered saline to affect subsequent malondialdehyde assays. This peroxidation did not occur at -196 °C. The ratio of oxidized to reduced glutathione increased with storage at -20 °C and the level of conjugated dienes increased progressively. The addition of a specific free radical scavenger, Superoxide dismutase (200 u/ml) reduced the level of malondialdehyde (P < 0.001) during -20 °C storage for periods of 28 days but failed to prevent the changes in the glutathione ratio or dienes. Storage in a less specific free radical scavenger, 0.25 molar sucrose/EDTA, instead of phosphatebuffered saline totally prevented the malondialdehyde production over similar storage periods. © 1992.