[Activity of carbohydratephosphate metabolism enzymes in liver slices after freezing and thawing]

Activity of hexokinase, phosphorylase, glucoso-6-phosphate dehydrogenase lactate-dehydrogenase was studied in liver slices, homogenate and supernatant fraction after freezing at a rate of 1 degree/min down to -30 degrees C. The enzyme activity in homogenate and supernatant fraction does not change after freezing. A significant reduction in the activity of most enzymes that is followed by an increase in their activity in the freezing medium was observed in the experiments. Cryoprotectant polyethylene glycol, mol. wt. 300 and 1,000 (PEG-300 and PEG-1,000), partially prevents the observed changes in the enzyme activity; PEG-1,000 is more effective than PEG-300. Experimental results show that the main reason for the reduction of the enzyme activity observed after freezing the tissue slices is a decrease in the volume of intracellular enzyme proteins due to their leakage from the injured cellular elements into the exocellular medium.