[Effect of deep freezing on isolated rat liver lysosomes]

The level of the non--sedimentating activity of acid hydrolases (deoxyribonuclease, phosphatase, cathepsins) and electron microscopy of lysosomes has been studied after freezing to --30 degrees, --70 degrees, --140 degrees and --196 degrees. It has been found that enzyme solubilistion and lysosome ultrastructure distortion are mostly marked in the temperature range between 0 degrees and --30 degrees C. Additional membrane damage is observed in the temperature range from --140 degrees to --196 degrees C. It is suggested that not only physico-chemical changes during phase transitions of free water in the freezing medium but also recrystallization processes and the freezing-out of water structurally bound with membranes may contribute to mechanism of lysosome cryoinjury.