ALTERATION OF COLLAGENOUS PROTEIN PROFILE IN CONGESTIVE-HEART-FAILURESECONDARY TO MYOCARDIAL-INFARCTION

The rat model of myocardial infarction is characterized by progressive cardiac hypertrophy and failure. Rats with infarcts greater than 30% of the left ventricle exhibited early and moderate stages of heart fai lure 4 and 8 weeks after the occlusion of the left coronary artery, re spectively. As heart failure is usually associated with remodeling of the extracellular matrix, a histological and biochemical study of card iac collagenous proteins was carried out using failing hearts. Total c ollagen content in the right ventricle increased at 2, 4, and 8 weeks following occlusion of the left coronary artery whereas such a change in viable left ventricle was seen after 4 and 8 weeks. Total cardiac h ydroxyproline concentration was increased in both right and left ventr icular samples from the infarcted animals when compared to those of co ntrol; this increase was due to elevation of pepsin-insoluble collagen fraction. The myocardial noncollagenous/collagenous protein ratio was decreased in experimental right and left ventricular samples when com pared to control samples. These findings suggest that an increase in c ross-linking of cardiac collagen as well as disparate synthesis of col lagenous and noncollagenous proteins occurs in this model of congestiv e heart failure.