Different changes in the cytosole creatine kinase isoenzymes from heart ofadult and old rats during stress

We have shown that immobilization stress causes changes in the spectrum of the heart's cytosole creatine kinase isoenzymes. In myocardium adult immobi lized rats, MM isoenzyme is decreased and MB and BB isoenzymes are increase d compared to intact animals. The pattern of isoenzyme response in old and adult rats was different. Immobilization of old rat caused an increase of M M and a decrease of MB isoenzyme in the heart's creatine kinase isoenzyme s pectrum. We suggest that this change in the creatine kinase isoenzyme spect rum in the myocardium of adult rats plays an adaptive role, increasing the effectiveness of its performance during stress. In old rats, apparent chang es in the creatine kinase isoenzyme spectrum promote a disturbance of myoca rdial energy metabolism. (C) 1999 Elsevier Science Inc. All rights reserved .