Oxidative and phosphorylative activities were measured polarographically in mitochondria isolated from the right and left ventricles of normal and chronically stressed dog hearts. Chronic myocardial stress was produced experimentally by surgical procedures (combined tricuspid insufficiency and pulmonary stenosis, pulmonary insufficiency, aortic stenosis, aortic insufficiency, Potts's anastomosis) and by inducing thyrotoxicosis. Experimental stress periods ranged from 332 to 608 days. Some of the dogs had overt symptoms of congestive heart failure at the time they were killed.Mitochondria isolated from the stressed hearts had abnormally high values for oxidative activity and respiratory control ratios when incubated in the presence of malate-pyruvate. In the presence of succinate, they had either normal or slightly elevated values for oxidative activity and respiratory control ratios. No differences were found between mitochondria from normal and stressed hearts with regard to the efficiency (ADP/O) of oxidative phosphorylation. Estimates of mitochondrial protein per gram of myocardial tissue indicated that the stressed hearts contained normal amounts of mitochondria. The results of this study suggest that the mitochondrial oxidative and phosphorylative capabilities of the chronically stressed myocardium are not impaired.ADDITIONAL KEY WORDS mitochondrial function mitochondrial respiration mitochondrial respiratory control experimental chronic congestive heart failure mitochondrial metabolism• Chronic stress on the heart often results in a gradual deterioration of myocardial performance as evidenced clinically by congestive heart failure. Although this deterioration has long been considered to be a reflection of a biochemical abnormality in the myocardium, positive identification of this abnormality has not been achieved. The present report describes a search for biochemical abnormalities in mitochondria isolated from chronically stressed dog hearts, some of which appeared to be in chronic failure.From the Heart Biochemistry Research Laboratory of the Cardiovascular Service, Division of Thoracic Surgery, and Departments of Surgery and Physiological Chemistry, Ohio State University College of Medicine, Columbus, Ohio 43210. These studies were supported by U. S. Public Health Service Research Grant HE 05273-06 from the National Heart Institute.Accepted for publication May 20, 1968. The results of previous studies on the condition of mitochondria in the chronically stressed or failing heart are conflicting. Mitochondrial function was reported to be normal in some of these studies (1-4), whereas in others a reduction in oxidative activity (5-7), respiratory control ratios (6) and efficiency of oxidative phosphorylation (5-7) was observed. The factors responsible for these divergent results have not been clear. To test the possibility that some of the conflict in these reports is due to differences in the means by which myocardial stress was produced, we have measured oxidative activity, respiratory control...
The amount and state of binding of three lysosomal acid hydrolases, acid phosphatase, cathepsin, and /3-glucuronidase, were studied in canine cardiac muscle following severe asphyxia and deep hypothermia. The studies were done on adult mongrel dogs anesthetized with sodium pentobarbital. Asphyxia was produced by tracheal occlusion, and was maintained until the onset of cardiac arrest (6 to 10 min). Hypothermic conditions were achieved by placing the heart on partial bypass through a heat exchanger. The heart was cooled to 6 to 10°C and held at this temperature for 30 min while circulation and respiration were maintained by artificial means. Control dogs were subjected to similar surgical procedures. Immediately following the experiments, the whole hearts were removed, cooled to 0 to 4°C, homogenized, and fractionated into supernatant and lysosomal fractions. The levels of bound and free acid hydrolases were estimated in the whole homogenates and fractions. Asphyxia produced a large shift of acid hydrolase activity from a bound form to a free form, as evidenced by elevated ratios of free to bound activity in the whole homogenates and elevated ratios of supernatant to lysosomal activity with respect to the fractions. Hypothermia did not alter the binding status of the lysosomal enzymes. These findings suggest that lysosomal enzymes play a major role in asphyxic damage to the heart. ADDITIONAL KEY WORDS anoxia hypoxia cathepsin jS-glucuronidase acid phosphatase• The functional manifestations of injury to the myocardium following a short period of severe hypoxia or deep hypothermia are well known. Little is known, however, of the biochemical events which are the basis for this injury.The normal canine heart deprived of oxygen continues to function for only about 5 min (1). If this state persists for more than a few min-
Aortic arch atresia is a comparatively rare congenital anomaly that commonly produces heart failure and death in early infancy. A new operative procedure is described which is applicable to type I, where the atresia lies distal to the left subclavian artery. It provides a lumen that is equal to the descending thoracic aorta by using the conjoined orifices of the left subclavian and common carotid arteries for anastomosis to the distal thoracic aorta. The chief advantage of this method is that it not only provides a vascular bridge with a lumen equal to the distal thoracic aorta, but also assures normal growth potential.
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