[Overall activity and isoenzymatic spectrum of liver lactate dehydrogenase in hypobiotic rats]

A total activity and isoenzyme spectrum of LDH from liver tissue were studied in rats, which were cooled down to the body temperature of 18-22 degrees and were kept in conditions of artificial hypobiosis for a long time (24 and 30 hrs). In cooled rats an increase in total LDH activity was observed. The increase might be a reflection of a stress-reaction to cooling since the method of developing of a hypobiosis involved an incomplete depression of thermoregulation. Subsequent extention of hypobiosis caused a gradual decrease in the total activity of LDH from liver tissue. The LDH activity reached values which were lower than the initial level. This phenomenon was probably due to attenuation of the stress-reaction and to a decrease in metabolic processes under effect of hypothermia. The alterations noted in the total LDH activity were determined by changes in the activity of a prevailing isoenzyme--LDH5. The increase in the LDH5 activity was assumed to be associated with activation of neoglucogenesis and determined by an orientation of the LDH-reaction in the direction of pyruvate.