EXPERIMENTAL MYOCARDIAL-INFARCTION WITH CARTILAGINOUS AND OSSEOUS METAPLASIA IN SHR AND WKY RATS

Myocardial infarction was induced by ligation of the coronary artery i n fifteen 32-week-old male spontaneously hypertensive rats (SHR) and f ifteen 32-week-old male normotensive Wistar-Kyoto rats (WKY). Age-matc hed male SHR (n=6) and WKY (n=7) without the operation were used as no n-infarcted control rats. Four weeks after the operation, cartilaginou s metaplasia and osseous metaplasia were observed histopathologically in all SHR and 13 of the 15 WKY with myocardial infarction, but not in the control rats. The mean rates of infarction to the heart and the m ean areas of metaplasia per rat showing metaplasia were greater in SHR than in WKY. The metaplastic areas were well correlated with the infa rct percentage in SHR. It is therefore considered that extensive myoca rdial infarction is associated with the pathogenesis of cartilaginous and osseous metaplasia.