VARIATION IN SERUM CREATINE-PHOSPHOKINASE ACTIVITY AS INDICATED IN 2-PHASE EMC-D VIRUS-INDUCED MYOCARDITIS

In this study, myocardial damage in the D-variant of encephalomyocardi tis (EMCD) virus-induced myocarditis has been investigated consecutive ly by measuring serum creatine phosphokinase (CPK) activity. CPK activ ity in 8 week-old male BALB/cAJcI mice inoculated with EMC-D virus inc reased to a peak at 4 or 5 days postinoculation (DPI) and then gradual ly decreased. The CPK activity rose again after 7 DPI until it reached a second peak. In view of the kinetics of CPK activity, two-phase (ea rly and late phase) myocardial damage in EMC virus infection were cons idered. In the late phase, an increase in cellular infiltration in the myocardium and a decrease in viral titer in the heart were observed I t was therefore suspected that the increase in CPK in the late phase m ay be caused by cellular infiltration, but not by viral replication. I n our results, we suggested that a serial measurement of serum CPK act ivity might be a useful method for throwing more light on the myocardi al damage caused by the autoimmune response. We also used a pathologic al (TUNEL) method to detect apoptotic cells and some apoptotic myocyte s in the myocardium in late phase EMC virus-induced myocarditis.