Thin myofilament proteins in norm and heart failure. I. Polymerizability of myocardial Straub actin in acute and chronic heart failure.

The reduced and intrinsic viscosities of myocardial Straub F-actin from the left ventricle of a practically healthy man were equal to 3.05 +/- 0.2 and 2.

Superprecipitation of hybrid actomyosin containing pathologic actin from failing hearts of adults and infants.

Superprecipitation (SP) of artificial actomyosin, obtained by hybridization of Straub actin from the human myocardium with myosin of normal animal hearts was studied. Actin was prepared from the myocardium of persons who died of congestive heart failure and various non-cardiac diseases, as well as of infants whose death resulted from toxic pneumonia complicated or not with heart failure. It was shown that, in the control hybrid actomyosin, the substitution of normal Straub actin by that from the failing heart resulted in decrease of both the rate and extent of SP.

[Polymerization of Straub's actin in patients with myocardial infarction and in experimental occlusion of coronary arteries].

Rates of actin polymerization and of contractility of myocardial glycerinated fibers (the myofibrillar contractile system) were found to be decreased in patients with myocardium infarction and in experimental heart ischemia. The phenomena were noted within the earliest period under study (I hr after development of ischemia). Causes of the decrease in the rates of actin polymerization and of the myofibrillar contractility did not involve hypoxia and acidosis.