ALTERATION OF EXTRACELLULAR-MATRIX IN DILATED CARDIOMYOPATHIC HAMSTERHEART

The purpose of this study was to characterize the collagen in heredita ry dilated cardiomyopathic hamster hearts, and to examine the particip ation of the collagen in the occurrence and progression of cardiomyopa thy. BIO 53.58 hamsters (5, 10, 20 weeks old) were used as the model o f dilated cardiomyopathy. Flb hamsters were used as controls. The coll agen content was almost constant at any age in the Flb hamsters, but i ncreased with age in BIO 53.58 hamsters. Type III collagen increased s ignificantly in BIO 53.58 hamsters at 10 weeks. The acetic acid solubi lity of collagen decreased in BIO 53.58 hamsters as the fibrosis progr essed, but was unchanged in controls. Reducible crosslinks showed a te ndency to decrease progressively in BIO 53.58 hamsters. There were no differences between Flb and BIO 53.58 hamsters at 5 weeks, but its exp ression in BIO 53.58 hamsters at 10 and 20 weeks of age increased comp ared to Flb controls. These findings indicate that in the early phase of cardiomyopathy the extracellular matrix of the myocardium is rich i n type III collagen. In the later phase, the matrix resembles that of hard tissues, whose collagen is mainly of type I collagen and is insol uble. These data suggest that the increased collagen synthesis may imp air the cardiac function in the development of cardiomyopathy.