Contractility and Extractability of Heart Actomyosin After Death

The contractility and extractability of actomyosin and proteins prepared from dogs ' heart im-mediately, and one hour after death were compared. The yield of total and soluble proteins and of actomyosin was found to be identical. In addition, there was no difference between the after-loaded contractions of actomyosin bands of fresh preparation and those obtained one hour after death. STUDIES on patients suffering from con-gestive failure have shown no abnor-mality in the extraction and utilization of glucose, pyruvate, lactate, fatty acids, amino acids and ketone bodies by the human heart. This finding has suggested that the basic defect in the heart muscle in myocardial failure is primarily in mechanisms concerned with energy utilization.1 Similar conclusions were reached by Benson2 who, by producing experi-mental chronic failure in dogs, was able to show that actomyosin from failing hearts differed from that of normal hearts. To the present, no experiments have been published which deal with changes of actomyosin of failing human heart muscle. Such investigations could be carried out by comparing actomyosin obtained from heart muscle of patients who died of con-gestive failure with actomyosin obtained from normal hearts. Since these studies are based on the premise that characteristic properties of actomyosin do not change for a brief period after death, an investigation was begun which deals with a comparison of properties of acto-myosin prepared from dogs ' hearts immedi-ately after death and one hour later. METHODS Eleven adult dogs were anesthetized by the intra-venous injection of sodium pentobarbital (30 mg./Kg. weight). The chest was then entered and approximately 15 Gm. of left ventricular muscl