1993 Volume 30 Issue 7 Pages 617-621
The severity and frequency of atherosclerosis, diabetes, and ischemic heart disease, which affect cardiac function, increase with aging. Although there are many reports about hemodynamic and histpathological studies about aging hearts, there are very few studies on changes in structural proteins in aging hearts. We investigated the contractile proteins of the left ventricles in rats aged 6, 12 and 125 weeks using two-dimensional electrophoresis. There were no difference in structural proteins in heart between 6-week and 12-week-old rats. The contents of myosin heavy chain, myosin light chain 2, actin, troponin-I in 125-week-old rats decreased compared with those of 12-week-old rats. Myosin heavy chain, which is one component of myosin, interacts with actin and changes chemical energy to mechanical energy. Therefore its decrease leads to a decline in myocardial contractility. These results seem to indicate one of the most important changes in the aging rat heart, as well as impairment in relaxation by the increase of interstitial fibrosis and decline of Ca uptake by sarcoplasmic reticulum.