Discrimination of recent ischemic myocardial changes in WHHLMI rabbits from the findings of postmortem degeneration.

To distinguish recent ischemic myocardial changes in myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits from general postmortem myocardial degeneration, we examined hearts of WHHLMI rabbits after sudden death and postmortem hearts of non-atherogenic rabbits. Hearts of 8 WHHLMI rabbits were excised within 30 min of sudden death and hearts of 27 non-atherosclerotic rabbits were excised at designated periods after sacrifice. A large number of myocardial cells from WHHLMI rabbits exhibited features characteristic of ischemia (intercellular gap, intracellular edema, eosinophilia, disappearance of myocardial cells, indistinct nuclei, wavy myocardial fibers) simultaneously at regions close to proximal occluded coronary arteries. Although postmortem hearts of non-atherosclerotic rabbits exhibited similar characteristics, several features characteristic of autolyzed myocytes were also randomly observed in the left ventricle wall. Each feature was detected independently in myocardial cells or regions of the ventricle wall. In conclusion, we found several unique characteristics associated with myocardial infarction which enable discrimination between recent ischemic myocardial changes and myocardial degeneration following death.