Abnormalities in Cardiac Contractile Proteins and Cardiac Dysfunction
Multiple changes occur in the cardiac contractile protein assembly that contribute in concert to altered contractile performance in different pathologic states. It has been shown that cardiac myosin in some species exists in three isoenzymic forms and that these may vary depending on the animal’s age, species, and physiologic or pathologic state . Isoenzymic changes in myosin can account for the changes in ATPase activity observed in a variety of models of cardiac hypertrophy . A great deal of work in cardiac hypertrophy and failure has focused upon alterations in myosin ATPase activity and isoenzymes. Abnormalities in myofibrillar dose-response curves have been observed in experimental diabetic cardiomyopathy [3,4], pressure induced overload with and without congestive heart failure, ischemic cardiomyopathy, and idiopathic cardiomyopathy [5,6]. However, alterations in myosin have not been observed in humans. Thus, some component or components in the myofibrillar assembly other than myosin must be responsible for the decrement in cardiac funcition associated with heart disease in humans.
KeywordsATPase Activity Contractile Dysfunction Cardiac Myosin Myofibrillar ATPase Myosin ATPase Activity
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